Tổng hợp đề thi thử tiếng anh thpt quốc gia (Đề số 13)

Mark the letter A, B, C, or D on your answer sheet to indicate the word whose underlined part differs from the other three in pronunciation in each of the following questions.

Mark the letter A, B, C, or D on your answer sheet to indicate the word that differs from the other three in the position of primary stress in each of the following questions.

Mark the letter A, B, C, or D on your answer sheet to indicate the word that differs from the other three in the position of primary stress in each of the following questions.

Mark the letter A, B, C, or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions.

It is believed that in the near future robots will be used to doing things such as cooking.

Mark the letter A, B, C, or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions.

It is becoming extremely difficult to grow enough to feed the worlds rapidly increased population

Mark the letter A, B, C, or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions.

Jack had to skip breakfast; otherwise, he will be late for class.

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.

I decided to go to the library as soon as I _______.

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.

The restaurant has a very ___ menu. Every day there are several delicious dishes to choose from.

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.

It seems that you have to cope with the stresses and strains of the job, ___________?

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.

Do you know who ___________ the fact that sound travels in waves?

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.

I always enjoy our school _______to France.

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.

Most people prefer ________ at home rather than ________out on rainy days.

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.

You can go to the party tonight _______ you are sober when you come home.

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________ wait for no man.

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I usually buy my clothes_____. It’s cheaper than going to the dress maker.

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.

In most _____ developed countries, up to 50% of _____ population enters higher education at

some time in their lives.

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.

Prices quoted in this package include _____ hours of Internet access for one month.

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.

The school was closed for a month because of serious ………… of fever.

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.

Marie Curie, ________, was awarded a Nobel Prize for her work.

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.

Since Elizabeth Barrett Browning’s father never approved of ________ Robert Browning, the

couple eloped to Italy where they lived and wrote.

Mark the letter A, B, C, or D on your answer sheet to indicate the most suitable response to complete each of the following exchanges.

Peter: “Thanks a lot for your wonderful gift.” – Mary: “________”

Mark the letter A, B, C, or D on your answer sheet to indicate the most suitable response to complete each of the following exchanges.

“Excuse me, is anybody sitting here?” – “________”

Mark the letter A, B, C, or D on your answer sheet to indicate the word(s) OPPOSITE in meaning to the underlined word(s) in each of the following questions.

The new laws to conserve wildlife in the area will come into force next month

Mark the letter A, B, C, or D on your answer sheet to indicate the word(s) OPPOSITE in meaning to the underlined word(s) in each of the following questions.

The farmers removed some underdeveloped trees to improve the growth of the rest.

Mark the letter A, B, C, or D on your answer sheet to indicate the word(s) CLOSEST in meaning to the underlined word(s) in each of the following questions.

He was asked to account for his presence at the scene of the crime.

Mark the letter A, B, C, or D on your answer sheet to indicate the word(s) CLOSEST in meaning to the underlined word(s) in each of the following questions.

When being interviewed, you should concentrate on what the interviewer is saying or asking you.

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that is closest in meaning to each of the following questions.

If it hadn’t been for his carelessness, we would have finished the work.

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that is closest in meaning to each of the following questions.

The hostess made every effort to see that her guests got the food and drinks they wanted.

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that is closest in meaning to each of the following questions.

“If I were you, I would not choose to write about such a sensitive topic,” the teacher said.

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that best combines each pair of sentences in the following questions.

He felt very tired. However, he was determined to continue to climb up the mountain.

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that best combines each pair of sentences in the following questions.

She heard the news of the death of her father. She fainted.

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the

correct word or phrase that best fits each of the numbered blanks. Fill in the appropriate word in question 33

Wind, water, air, ice and heat all work to cause erosion. As the wind blows over the land, it often (33)_______ small grains of sand. When these grains of sand strike against solid rocks, the rocks are slowly worn away. In this way, (34)_______ very hard rocks are worn away by the wind.

When particles of rocks or soil became loosened in any way, running water carries them down the hillsides. Some rocks and soil particles are carried into streams and then into the sea.

Land that is covered with trees, grass and other plants wear away very slowly, and so loses very (35)_______ of its soil. The roots of plants help to hold the rocks and soil in place. Water that falls on grasslands runs away more slowly than water that falls on bare ground. Thus, forests and grasslands help to slow down erosion.

Even where the land is (36)_______ covered with plants, some erosion goes on. In the spring, the melting snow turns into a large quantity of water that then runs downhill in streams. As a stream carries away some of the soil, the stream bed gets deeper and deeper. (37)_______ thousands of years of such erosion, wide valleys are often formed.

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the

correct word or phrase that best fits each of the numbered blanks. Fill in the appropriate word in question 34

Wind, water, air, ice and heat all work to cause erosion. As the wind blows over the land, it often (33)_______ small grains of sand. When these grains of sand strike against solid rocks, the rocks are slowly worn away. In this way, (34)_______ very hard rocks are worn away by the wind.

When particles of rocks or soil became loosened in any way, running water carries them down the hillsides. Some rocks and soil particles are carried into streams and then into the sea.

Land that is covered with trees, grass and other plants wear away very slowly, and so loses very (35)_______ of its soil. The roots of plants help to hold the rocks and soil in place. Water that falls on grasslands runs away more slowly than water that falls on bare ground. Thus, forests and grasslands help to slow down erosion.

Even where the land is (36)_______ covered with plants, some erosion goes on. In the spring, the melting snow turns into a large quantity of water that then runs downhill in streams. As a stream carries away some of the soil, the stream bed gets deeper and deeper. (37)_______ thousands of years of such erosion, wide valleys are often formed.

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the

correct word or phrase that best fits each of the numbered blanks. Fill in the appropriate word in question 33

Wind, water, air, ice and heat all work to cause erosion. As the wind blows over the land, it often (33)_______ small grains of sand. When these grains of sand strike against solid rocks, the rocks are slowly worn away. In this way, (34)_______ very hard rocks are worn away by the wind.

When particles of rocks or soil became loosened in any way, running water carries them down the hillsides. Some rocks and soil particles are carried into streams and then into the sea.

Land that is covered with trees, grass and other plants wear away very slowly, and so loses very (35)_______ of its soil. The roots of plants help to hold the rocks and soil in place. Water that falls on grasslands runs away more slowly than water that falls on bare ground. Thus, forests and grasslands help to slow down erosion.

Even where the land is (36)_______ covered with plants, some erosion goes on. In the spring, the melting snow turns into a large quantity of water that then runs downhill in streams. As a stream carries away some of the soil, the stream bed gets deeper and deeper. (37)_______ thousands of years of such erosion, wide valleys are often formed.

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the

correct word or phrase that best fits each of the numbered blanks. Fill in the appropriate word in question 36

Wind, water, air, ice and heat all work to cause erosion. As the wind blows over the land, it often (33)_______ small grains of sand. When these grains of sand strike against solid rocks, the rocks are slowly worn away. In this way, (34)_______ very hard rocks are worn away by the wind.

When particles of rocks or soil became loosened in any way, running water carries them down the hillsides. Some rocks and soil particles are carried into streams and then into the sea.

Land that is covered with trees, grass and other plants wear away very slowly, and so loses very (35)_______ of its soil. The roots of plants help to hold the rocks and soil in place. Water that falls on grasslands runs away more slowly than water that falls on bare ground. Thus, forests and grasslands help to slow down erosion.

Even where the land is (36)_______ covered with plants, some erosion goes on. In the spring, the melting snow turns into a large quantity of water that then runs downhill in streams. As a stream carries away some of the soil, the stream bed gets deeper and deeper. (37)_______ thousands of years of such erosion, wide valleys are often formed.

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the

correct word or phrase that best fits each of the numbered blanks. Fill in the appropriate word in question 37

Wind, water, air, ice and heat all work to cause erosion. As the wind blows over the land, it often (33)_______ small grains of sand. When these grains of sand strike against solid rocks, the rocks are slowly worn away. In this way, (34)_______ very hard rocks are worn away by the wind.

When particles of rocks or soil became loosened in any way, running water carries them down the hillsides. Some rocks and soil particles are carried into streams and then into the sea.

Land that is covered with trees, grass and other plants wear away very slowly, and so loses very (35)_______ of its soil. The roots of plants help to hold the rocks and soil in place. Water that falls on grasslands runs away more slowly than water that falls on bare ground. Thus, forests and grasslands help to slow down erosion.

Even where the land is (36)_______ covered with plants, some erosion goes on. In the spring, the melting snow turns into a large quantity of water that then runs downhill in streams. As a stream carries away some of the soil, the stream bed gets deeper and deeper. (37)_______ thousands of years of such erosion, wide valleys are often formed.

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 1 to 5.

A team of Russian scientists has challenged the theory that the woolly mammoths became extinct 10,000 years ago at the end of the Ice Age. The scientists have reported that the beasts may have survived until 2000 B.C. on an island off the coast of Siberia, where researchers uncovered 29 fossilized woolly mammoth teeth ranging in age from 4,000 to 7,000 years. The question to be asked now is, how did these prehistoric pachyderms survive in their island environment? One possibility is that they adapted to their confined surroundings by decreasing their bulk. This theory is based on their smaller tooth size, which has led scientists to believe that they were only 6 feet tall at the shoulder compared with 10 feet of their full-sized counterpart. But would this be enough to enable them to survive thousands of years beyond that of other mammoths? Researchers are still working to uncover the reasons for this isolated group's belated disappearance.

With which topic is this passage mainly concerned?

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 1 to 5.

A team of Russian scientists has challenged the theory that the woolly mammoths became extinct 10,000 years ago at the end of the Ice Age. The scientists have reported that the beasts may have survived until 2000 B.C. on an island off the coast of Siberia, where researchers uncovered 29 fossilized woolly mammoth teeth ranging in age from 4,000 to 7,000 years. The question to be asked now is, how did these prehistoric pachyderms survive in their island environment? One possibility is that they adapted to their confined surroundings by decreasing their bulk. This theory is based on their smaller tooth size, which has led scientists to believe that they were only 6 feet tall at the shoulder compared with 10 feet of their full-sized counterpart. But would this be enough to enable them to survive thousands of years beyond that of other mammoths? Researchers are still working to uncover the reasons for this isolated group's belated disappearance.

According to the passage, some researchers suggest that mammoths became extinct

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 1 to 5.

A team of Russian scientists has challenged the theory that the woolly mammoths became extinct 10,000 years ago at the end of the Ice Age. The scientists have reported that the beasts may have survived until 2000 B.C. on an island off the coast of Siberia, where researchers uncovered 29 fossilized woolly mammoth teeth ranging in age from 4,000 to 7,000 years. The question to be asked now is, how did these prehistoric pachyderms survive in their island environment? One possibility is that they adapted to their confined surroundings by decreasing their bulk. This theory is based on their smaller tooth size, which has led scientists to believe that they were only 6 feet tall at the shoulder compared with 10 feet of their full-sized counterpart. But would this be enough to enable them to survive thousands of years beyond that of other mammoths? Researchers are still working to uncover the reasons for this isolated group's belated disappearance.

The word "woolly" as used in line 1 refers to the animal's

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 1 to 5.

A team of Russian scientists has challenged the theory that the woolly mammoths became extinct 10,000 years ago at the end of the Ice Age. The scientists have reported that the beasts may have survived until 2000 B.C. on an island off the coast of Siberia, where researchers uncovered 29 fossilized woolly mammoth teeth ranging in age from 4,000 to 7,000 years. The question to be asked now is, how did these prehistoric pachyderms survive in their island environment? One possibility is that they adapted to their confined surroundings by decreasing their bulk. This theory is based on their smaller tooth size, which has led scientists to believe that they were only 6 feet tall at the shoulder compared with 10 feet of their full-sized counterpart. But would this be enough to enable them to survive thousands of years beyond that of other mammoths? Researchers are still working to uncover the reasons for this isolated group's belated disappearance.

The author uses the word "counterpart" in line 7 to refer to

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 1 to 5.

A team of Russian scientists has challenged the theory that the woolly mammoths became extinct 10,000 years ago at the end of the Ice Age. The scientists have reported that the beasts may have survived until 2000 B.C. on an island off the coast of Siberia, where researchers uncovered 29 fossilized woolly mammoth teeth ranging in age from 4,000 to 7,000 years. The question to be asked now is, how did these prehistoric pachyderms survive in their island environment? One possibility is that they adapted to their confined surroundings by decreasing their bulk. This theory is based on their smaller tooth size, which has led scientists to believe that they were only 6 feet tall at the shoulder compared with 10 feet of their full-sized counterpart. But would this be enough to enable them to survive thousands of years beyond that of other mammoths? Researchers are still working to uncover the reasons for this isolated group's belated disappearance.

According to the scientists, the woolly mammoths may have managed to survive because they

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 1 to 8.

As heart disease continues to be the number-one killer in the United States, researchers have become increasingly interested in identifying the potential risk factors that trigger heart attacks. High-fat diets and "life in the fast lane" have long been known to contribute to the high incidence of heart failure. But according to new studies, the list of risk factors may be significantly longer and quite surprising.

Heart failure, for example, appears to have seasonal and temporal patterns. A higher percentage of heart attacks occur in cold weather, and more people experience heart failure on Monday than on any other day of the week. In addition, people are more susceptible to heart attacks in the first few hours after waking. Cardiologists first observed this morning phenomenon in the mid-1980, and have since discovered a number of possible causes. An early-morning rise in blood pressure, heart rate, and concentration of heart stimulating hormones, plus a reduction of blood flow to the heart, may all contribute to the higher incidence of heart attacks between the hours of 8:00 A.M. and 10:00 A.M.

In other studies, both birthdays and bachelorhood have been implicated as risk factors. Statistics reveal that heart attack rates increase significantly for both females and males in the few days immediately preceding and following their birthdays. And unmarried men are more at risk for heart attacks than their married counterparts. Though stress is thought to be linked in some way to all of the aforementioned risk factors, intense research continues in the hope of further comprehending why and how heart failure is triggered.

What does the passage mainly discuss?

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 1 to 8.

As heart disease continues to be the number-one killer in the United States, researchers have become increasingly interested in identifying the potential risk factors that trigger heart attacks. High-fat diets and "life in the fast lane" have long been known to contribute to the high incidence of heart failure. But according to new studies, the list of risk factors may be significantly longer and quite surprising.

Heart failure, for example, appears to have seasonal and temporal patterns. A higher percentage of heart attacks occur in cold weather, and more people experience heart failure on Monday than on any other day of the week. In addition, people are more susceptible to heart attacks in the first few hours after waking. Cardiologists first observed this morning phenomenon in the mid-1980, and have since discovered a number of possible causes. An early-morning rise in blood pressure, heart rate, and concentration of heart stimulating hormones, plus a reduction of blood flow to the heart, may all contribute to the higher incidence of heart attacks between the hours of 8:00 A.M. and 10:00 A.M.

In other studies, both birthdays and bachelorhood have been implicated as risk factors. Statistics reveal that heart attack rates increase significantly for both females and males in the few days immediately preceding and following their birthdays. And unmarried men are more at risk for heart attacks than their married counterparts. Though stress is thought to be linked in some way to all of the aforementioned risk factors, intense research continues in the hope of further comprehending why and how heart failure is triggered.

The word "potential" could best be re-placed by which of the following?

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 1 to 8.

As heart disease continues to be the number-one killer in the United States, researchers have become increasingly interested in identifying the potential risk factors that trigger heart attacks. High-fat diets and "life in the fast lane" have long been known to contribute to the high incidence of heart failure. But according to new studies, the list of risk factors may be significantly longer and quite surprising.

Heart failure, for example, appears to have seasonal and temporal patterns. A higher percentage of heart attacks occur in cold weather, and more people experience heart failure on Monday than on any other day of the week. In addition, people are more susceptible to heart attacks in the first few hours after waking. Cardiologists first observed this morning phenomenon in the mid-1980, and have since discovered a number of possible causes. An early-morning rise in blood pressure, heart rate, and concentration of heart stimulating hormones, plus a reduction of blood flow to the heart, may all contribute to the higher incidence of heart attacks between the hours of 8:00 A.M. and 10:00 A.M.

In other studies, both birthdays and bachelorhood have been implicated as risk factors. Statistics reveal that heart attack rates increase significantly for both females and males in the few days immediately preceding and following their birthdays. And unmarried men are more at risk for heart attacks than their married counterparts. Though stress is thought to be linked in some way to all of the aforementioned risk factors, intense research continues in the hope of further comprehending why and how heart failure is triggered.

The phrase "susceptible to" in line 6 could best be replaced by

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 1 to 8.

As heart disease continues to be the number-one killer in the United States, researchers have become increasingly interested in identifying the potential risk factors that trigger heart attacks. High-fat diets and "life in the fast lane" have long been known to contribute to the high incidence of heart failure. But according to new studies, the list of risk factors may be significantly longer and quite surprising.

Heart failure, for example, appears to have seasonal and temporal patterns. A higher percentage of heart attacks occur in cold weather, and more people experience heart failure on Monday than on any other day of the week. In addition, people are more susceptible to heart attacks in the first few hours after waking. Cardiologists first observed this morning phenomenon in the mid-1980, and have since discovered a number of possible causes. An early-morning rise in blood pressure, heart rate, and concentration of heart stimulating hormones, plus a reduction of blood flow to the heart, may all contribute to the higher incidence of heart attacks between the hours of 8:00 A.M. and 10:00 A.M.

In other studies, both birthdays and bachelorhood have been implicated as risk factors. Statistics reveal that heart attack rates increase significantly for both females and males in the few days immediately preceding and following their birthdays. And unmarried men are more at risk for heart attacks than their married counterparts. Though stress is thought to be linked in some way to all of the aforementioned risk factors, intense research continues in the hope of further comprehending why and how heart failure is triggered.

According to the passage, which of the following is NOT a possible cause of many heart attacks?

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 1 to 8.

As heart disease continues to be the number-one killer in the United States, researchers have become increasingly interested in identifying the potential risk factors that trigger heart attacks. High-fat diets and "life in the fast lane" have long been known to contribute to the high incidence of heart failure. But according to new studies, the list of risk factors may be significantly longer and quite surprising.

Heart failure, for example, appears to have seasonal and temporal patterns. A higher percentage of heart attacks occur in cold weather, and more people experience heart failure on Monday than on any other day of the week. In addition, people are more susceptible to heart attacks in the first few hours after waking. Cardiologists first observed this morning phenomenon in the mid-1980, and have since discovered a number of possible causes. An early-morning rise in blood pressure, heart rate, and concentration of heart stimulating hormones, plus a reduction of blood flow to the heart, may all contribute to the higher incidence of heart attacks between the hours of 8:00 A.M. and 10:00 A.M.

In other studies, both birthdays and bachelorhood have been implicated as risk factors. Statistics reveal that heart attack rates increase significantly for both females and males in the few days immediately preceding and following their birthdays. And unmarried men are more at risk for heart attacks than their married counterparts. Though stress is thought to be linked in some way to all of the aforementioned risk factors, intense research continues in the hope of further comprehending why and how heart failure is triggered.

Which of the following is NOT cited as a possible risk factor?

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 1 to 8.

As heart disease continues to be the number-one killer in the United States, researchers have become increasingly interested in identifying the potential risk factors that trigger heart attacks. High-fat diets and "life in the fast lane" have long been known to contribute to the high incidence of heart failure. But according to new studies, the list of risk factors may be significantly longer and quite surprising.

Heart failure, for example, appears to have seasonal and temporal patterns. A higher percentage of heart attacks occur in cold weather, and more people experience heart failure on Monday than on any other day of the week. In addition, people are more susceptible to heart attacks in the first few hours after waking. Cardiologists first observed this morning phenomenon in the mid-1980, and have since discovered a number of possible causes. An early-morning rise in blood pressure, heart rate, and concentration of heart stimulating hormones, plus a reduction of blood flow to the heart, may all contribute to the higher incidence of heart attacks between the hours of 8:00 A.M. and 10:00 A.M.

In other studies, both birthdays and bachelorhood have been implicated as risk factors. Statistics reveal that heart attack rates increase significantly for both females and males in the few days immediately preceding and following their birthdays. And unmarried men are more at risk for heart attacks than their married counterparts. Though stress is thought to be linked in some way to all of the aforementioned risk factors, intense research continues in the hope of further comprehending why and how heart failure is triggered.

The word "phenomenon" in line 7 refers to which of the following?

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 1 to 8.

As heart disease continues to be the number-one killer in the United States, researchers have become increasingly interested in identifying the potential risk factors that trigger heart attacks. High-fat diets and "life in the fast lane" have long been known to contribute to the high incidence of heart failure. But according to new studies, the list of risk factors may be significantly longer and quite surprising.

Heart failure, for example, appears to have seasonal and temporal patterns. A higher percentage of heart attacks occur in cold weather, and more people experience heart failure on Monday than on any other day of the week. In addition, people are more susceptible to heart attacks in the first few hours after waking. Cardiologists first observed this morning phenomenon in the mid-1980, and have since discovered a number of possible causes. An early-morning rise in blood pressure, heart rate, and concentration of heart stimulating hormones, plus a reduction of blood flow to the heart, may all contribute to the higher incidence of heart attacks between the hours of 8:00 A.M. and 10:00 A.M.

In other studies, both birthdays and bachelorhood have been implicated as risk factors. Statistics reveal that heart attack rates increase significantly for both females and males in the few days immediately preceding and following their birthdays. And unmarried men are more at risk for heart attacks than their married counterparts. Though stress is thought to be linked in some way to all of the aforementioned risk factors, intense research continues in the hope of further comprehending why and how heart failure is triggered.

word "trigger" as used in the first paragraph is closest in meaning to which of the following?

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 1 to 8.

As heart disease continues to be the number-one killer in the United States, researchers have become increasingly interested in identifying the potential risk factors that trigger heart attacks. High-fat diets and "life in the fast lane" have long been known to contribute to the high incidence of heart failure. But according to new studies, the list of risk factors may be significantly longer and quite surprising.

Heart failure, for example, appears to have seasonal and temporal patterns. A higher percentage of heart attacks occur in cold weather, and more people experience heart failure on Monday than on any other day of the week. In addition, people are more susceptible to heart attacks in the first few hours after waking. Cardiologists first observed this morning phenomenon in the mid-1980, and have since discovered a number of possible causes. An early-morning rise in blood pressure, heart rate, and concentration of heart stimulating hormones, plus a reduction of blood flow to the heart, may all contribute to the higher incidence of heart attacks between the hours of 8:00 A.M. and 10:00 A.M.

In other studies, both birthdays and bachelorhood have been implicated as risk factors. Statistics reveal that heart attack rates increase significantly for both females and males in the few days immediately preceding and following their birthdays. And unmarried men are more at risk for heart attacks than their married counterparts. Though stress is thought to be linked in some way to all of the aforementioned risk factors, intense research continues in the hope of further comprehending why and how heart failure is triggered.

Which of the following does the passage infer?