III. READING

a. Choose the word or phrase - a, b, c or d - that best fits the blank space in the following passage.

A desert is a special (46) _________ where only certain kinds of plants and animals can survive. All deserts have very little water. This means that only animals and plants that can (47) _________water for long periods of time can exist in the desert. Plants in the deserts are particularly (48)________to the dry and hot environment. One well-known desert plant is the cactus. (49) ________many desert plants, this plant has very tiny leaves. As plants lose most of their water (50) _________ their leaves, the small leaves of the cactus help to cut down water evaporation. There are some desert plants that do not have leaves at all. Some desert plants (51) _________ by avoiding the dry season altogether. During the dry season, this plant remains a seed and does not (52) _________ from the soil at all. When the rains come, this seed would grow very quickly into a plant. It would (53) _________rapidly and then scatter its seed before the dry season return. Desert animals have also learnt to adapt well to life in this region. The camel, for example, survives well in the desert because water can be (54) _________ in its body. Other desert animals include rodents such as mice. These animals need very little water (55) _________ they can get all the water they require from their food.

What is the main topic of the passage?