47 câu hỏi
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.
material
crucial
partial
financial
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
reign
leisure
neighbor
vein
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.
equip
vacant
secure
oblige
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.
prevention
implement
fertilize
enterprise
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.
It
the near future
be used to doing
such as
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
It
extremely difficult
to feed
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
skip breakfast
otherwise
will be
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 _______.
would finish what I did
finished what I did
finished what I was doing
finish what I did
The restaurant has a very _______ menu. Every day there are several delicious dishes to choose from
variable
variegated
various
varied
It seems that you have to cope with the stresses and strains of the job, ___________?
doesn’t it
don’t you
isn’t it
haven’t you
Do you know who ___________ the fact that sound travels in waves?
invented
discovered
developed
found
I always enjoy our school _______to France
excursion
journey
trip
travel
Most people prefer ________ at home rather than ________out on rainy days.
stay - go
staying - go
to stay - go
staying – going
You can go to the party tonight _______ you are sober when you come home.
as long as
as far as
as soon as
as well as
________ wait for no man
Tide and fire
Time and tide
Time and fire
Tide and time
I usually buy my clothes_____. It’s cheaper than going to the dress maker.
on the house
off the peg
in public
on the shelf
In most _____ developed countries, up to 50% of _____ population enters higher education at some time in their lives
Ø / Ø
the / Ø
Ø / the
the / a
Prices quoted in this package include _____ hours of Internet access for one month.
unwarranted
uncontrolled
unlimited
unrecoverable
The school was closed for a month because of serious ………… of fever.
outcome
outburst
outbreak
outset
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
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?
risk factors in heart attacks
seasonal and temporal patterns of heart attacks
cardiology in the 1980s
diet and stress as factors in heart attacks
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
Laura: “I’ve got two tickets for the exhibition.” - Mary: “______”
Oh, let’s go and get the tickets
That’s great! When is it?
Oh, anything else?
Thanks, I can’t afford the tickets.
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.
Host: “I’m terribly sorry for this inconvenience.” Guests: -"_______"
It’s mine. I came late
It’s not your fault
I’ll do better next time
Fine, thanks
Mark the letter A, B, C, or D on your answer sheet to indicate the word CLOSEST in meaning to the underlined word in each of the following questions.
In astronomy, a scale of magnitude from one to six denotes the brightness of a star
predicts
examines
contrasts
signifies
Mark the letter A, B, C, or D on your answer sheet to indicate the word CLOSEST in meaning to the underlined word in each of the following questions.
A lack of qualifications can be a major obstacle to finding a job.
impediment
encouragement
impetus
assistance
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.
His career in the illicit drug trade ended with the police raid this morning.
irregular
legal
elicited
secret
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.
Lakes occupy less than two percent of the Earth’s surface, yet they help sustain life.
prolong
obstruct
support
destroy
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.
I wish we had gone somewhere else for the holiday.
If only we went somewhere else for the holiday
It's a pity we didn't go there for the holiday
If we had gone for a holiday, I would have gone somewhere else
I regret not having gone somewhere else for the holiday
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.
It's ages since I last saw a Hollywood film
I saw a last Hollywood film since ages ago
I haven't seen a Hollywood film for a long time
I haven't seen any Hollywood films before
It's ages because I last saw a Hollywood film
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
"Why didn't you join your friends on the trip?" she asked
She asked me why I didn't join her friends on the trip
She wanted to know why I hadn't joined my friends on the trip
She asked for the reason I hadn't joined my friends on the trip
She asked me why didn't I join my friends on the trip
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:
If he could speak French, he would be able to get a job there
He couldn't speak French so he wasn't given the job there
He can't speak French, so he won't be able to get a job there
He can't speak French because he won't get a job there
He wishes he can speak French and worked there
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:
People say that Carter was the best director of his time
Carter is said to have been the best director of his time
Carter is said to be the best director of his time
Carter was said to be the best director of his time
It was said that Carter was the best director of his time
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 from 31 to 35.
The application (32)_________ for volunteers for the 15th Asian Games Doha 2006 is now closed. Organizers have been flooded with interest and have now filled all available roles. Any further (33)__________will have their details stored on file and will only be contacted in the event of any vacancies unexpectedly arising.
Over 30,000 men and women, not only from Qatar, but also from the Gulf (34)__________and even further afield, have volunteered to help out at Doha 2006 after more than two years of meetings and interviews. First of all, a big “thank you” to everyone for your enthusiasm and commitment in volunteering to give up some of your precious free time to become part of the Games of your Life. The (35)______ has been quite overwhelming and has far exceeded expectations.
“It shows that the Qatar public has embraced the (36)_________of the Games”, says Khaled Helaly, manager of the Doha 2006 Volunteers Programme
Điền ô số 32
growth
development
process
progress
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 from 31 to 35.
The application (32)_________ for volunteers for the 15th Asian Games Doha 2006 is now closed. Organizers have been flooded with interest and have now filled all available roles. Any further (33)__________will have their details stored on file and will only be contacted in the event of any vacancies unexpectedly arising.
Over 30,000 men and women, not only from Qatar, but also from the Gulf (34)__________and even further afield, have volunteered to help out at Doha 2006 after more than two years of meetings and interviews. First of all, a big “thank you” to everyone for your enthusiasm and commitment in volunteering to give up some of your precious free time to become part of the Games of your Life. The (35)______ has been quite overwhelming and has far exceeded expectations.
“It shows that the Qatar public has embraced the (36)_________of the Games”, says Khaled Helaly, manager of the Doha 2006 Volunteers Programme
Điền ô số 33
applicant
student
competitor
citizen
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 from 31 to 35.
The application (32)_________ for volunteers for the 15th Asian Games Doha 2006 is now closed. Organizers have been flooded with interest and have now filled all available roles. Any further (33)__________will have their details stored on file and will only be contacted in the event of any vacancies unexpectedly arising.
Over 30,000 men and women, not only from Qatar, but also from the Gulf (34)__________and even further afield, have volunteered to help out at Doha 2006 after more than two years of meetings and interviews. First of all, a big “thank you” to everyone for your enthusiasm and commitment in volunteering to give up some of your precious free time to become part of the Games of your Life. The (35)______ has been quite overwhelming and has far exceeded expectations.
“It shows that the Qatar public has embraced the (36)_________of the Games”, says Khaled Helaly, manager of the Doha 2006 Volunteers Programme
Điền ô số 34
Corner
address
section
region
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 from 31 to 35.
The application (32)_________ for volunteers for the 15th Asian Games Doha 2006 is now closed. Organizers have been flooded with interest and have now filled all available roles. Any further (33)__________will have their details stored on file and will only be contacted in the event of any vacancies unexpectedly arising.
Over 30,000 men and women, not only from Qatar, but also from the Gulf (34)__________and even further afield, have volunteered to help out at Doha 2006 after more than two years of meetings and interviews. First of all, a big “thank you” to everyone for your enthusiasm and commitment in volunteering to give up some of your precious free time to become part of the Games of your Life. The (35)______ has been quite overwhelming and has far exceeded expectations.
“It shows that the Qatar public has embraced the (36)_________of the Games”, says Khaled Helaly, manager of the Doha 2006 Volunteers Programme
Điền ô số 35
response
replace
repeat
rely
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 37 to 43.
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?
Some scientists have challenged a theory
Some small teeth have been discovered
Some mammoths lived longer than others
Some pachyderms survived on an island
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 37 to 43.
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
body size
feet size
hair
teeth
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 37 to 43.
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
shed their hair
grew smaller teeth
became herbivores
decreased in size
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 37 to 43.
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, the reason for the disappearance of the mammoths on the island is
that the temperature changed
is not yet known
that they were isolated
that larger mammoths killed them
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 37 to 43.
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.
Which of the following terms from the passage is NOT used to refer to the mammoths?
beasts
pachyderms
bulk
group
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 44 to 50.
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?
harmful
primary
unknown
possible
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 44 to 50.
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
aware of
affected by
accustomed
prone 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 44 to 50.
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?
decreased blood flow to the heart
increased blood pressure
lower heart rate
increase in hormones
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 44 to 50.
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?
having a birthday
getting married
eating fatty foods
being under stress
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 44 to 50.
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?
habit
illness
occurrence
activity
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 44 to 50.
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?
involve
affect
cause
encounter
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 44 to 50.
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?
We now fully understand how risk factors trigger heart attacks
We recently began to study how risk factors trigger heart attacks
We have not identified many risk factors associated with heart attacks
We do not fully understand how risk factors trigger heart attacks

