Desert plants fall into two sorts according to the way they deal with the problem of surviving drought. There are the drought―avoiders―those which persist（存留） only as seeds, ready to spring up when it rains, to flower quickly and produce another crop of seeds, and to die again. There are also the drought―resisters―those which have evolved various methods for strong water, locating underground water, or reducing their need for water by such devices as shedding their leaves. The drought―resisters are perennials(多年生植物),they manage to live from one rainy season to another, slowly growing bigger and bigger. Of these, the succulents(肉质的) is a small but interesting fraction(小部分). They may store water in their leaves, in their stems, or in underground containers.

  In the American deserts the best―known succulents are the cacti(仙人掌). They come in a wide range of sizes, from 50―foot tall giant saguaros(树形仙人掌) to tiny round cacti about the size of a thumb―nail. They take thick, cylindrical(圆柱体的) or even spherical forms, thereby exposing a minimum of evaporating surface to the air and light. They are leafless, except in youth, and then the leaves are small. Typically their surfaces are spiny, discouraging thirsty animals, and channeled like an accordion(手风琴), so the fleshy stem may expand quickly when the plant drinks and contract slowly as it uses up the water. The root system is widespread and shallow, with good reason; only about 3 per cent of the rain that falls on the desert penetrates to any significant depth into soil.

65. The passage classifies（将……分类） the desert plants according to___ .

A. the ways they take to deal with the typical climatic condition in desert

B. their shape

C. how they use water

D. when they produce their seeds

66. According to the passage, some desert plants drop their leaves ___ .

A. because the temperature is too high

B. so that the plants can evaporate less water

C. because they are drought resisters

D. so that the plants can store more water

67. What interests the author most when he or she mentions succulents is that ___ .

A. they take thick cylindrical or even spherical shape

B. they are best―known in America

C. they have many ways of containing water

D. some of them can be very tiny

68. The passage gives us an impression that ___ .

A. the desert plants are shaped in a way as if them were designed by somebody on purpose

B. more water is needed in desert so that more desert plants can grow there

C. more lands will be turned into desert if we do not try harder to save water in our daily life

D. the cacti are the most famous desert plants in America

Desert plants fall into two sorts according to the way they deal with the problem of surviving drought．There are the drought—avoiders—those which persist（存留） only as seeds, ready to spring up when it rains, to flower quickly and produce another crop of seeds, and to die again．There are also the drought—resisters—those which have evolved various methods for strong water, locating underground water, or reducing their need for water by such devices as shedding their leaves．The drought—resisters are perennials(多年生植物),they manage to live from one rainy season to another, slowly growing bigger and bigger．Of these, the succulents(肉质的) is a small but interesting fraction(小部分)．They may store water in their leaves, in their stems, or in underground containers．

In the American deserts the best—known succulents are the cacti(仙人掌)．They come in a wide range of sizes, from 50—foot tall giant saguaros(树形仙人掌) to tiny round cacti about the size of a thumb—nail．They take thick, cylindrical(圆柱体的) or even spherical forms, thereby exposing a minimum of evaporating surface to the air and light．They are leafless, except in youth, and then the leaves are small．Typically their surfaces are spiny, discouraging thirsty animals, and channeled like an accordion(手风琴), so the fleshy stem may expand quickly when the plant drinks and contract slowly as it uses up the water．The root system is widespread and shallow, with good reason; only about 3 per cent of the rain that falls on the desert penetrates to any significant depth into soil．

1．The passage classifies（将……分类） the desert plants according to

___ ．

A．the ways they take to deal with the typical climatic condition in desert

B．their shape

C．how they use water

D．when they produce their seeds

2．According to the passage, some desert plants drop their leaves ___ ．

A．because the temperature is too high

B．so that the plants can evaporate less water

C．because they are drought resisters

D．so that the plants can store more water

3．What interests the author most when he or she mentions succulents is that ___ ．

A．they take thick cylindrical or even spherical shape

B．they are best—known in America

C．they have many ways of containing water

D．some of them can be very tiny

4．The passage gives us an impression that ___ ．

A．the desert plants are shaped in a way as if them were designed by somebody on purpose

B．more water is needed in desert so that more desert plants can grow there

C．more lands will be turned into desert if we do not try harder to save water in our daily life

D．the cacti are the most famous desert plants in America

A desert is a place ________ is ________ nothing but sand．But a camel can walk in the desert for months without any food or water．

1. A.
   where; almost
2. B.
   there; nearly
3. C.
   where there; almost
4. D.
   that; almost

A desert is a beautiful land of silence and space. The sun shines, the wind blows, and time and space seem endless. Nothing is soft. The sand and rocks are hard, and many of the plants even have hard needles instead of leaves.

The size and location(分布) of the world’s deserts are always changing. Over millions of years, as climates change and mountains rise, new dry and wet areas develop. But within the last 100 yeas, deserts have been growing at a frightening speed. This is partly because of natural changes, but the greatest makers are humans.

Humans can make deserts, but humans can also prevent their growth. Algeria Mauritania is planting a similar wall around Nouakchott, the capital. Iran puts a thin covering of petroleum(石油) on sandy areas and plants trees. The oil keeps the water and small trees in the land, and men on motorcycles(摩托车) keep the sheep and goats away. The USSR and India are building long canals to bring water to desert areas.

In this passage, “needles” refers to _______.

A. small, thin pieces of steel.

B. long, thin pieces of branches.

C. small pointed growth on the stem(茎) of a plant.

D. small, thin pieces of sticks.

Which of the following is NOT true?

A. The greatest desert makers are humans.

B. There aren’t any living things in the deserts.

C. Deserts have been growing quickly.

D. The size of the deserts is always changing.

People in some countries are fighting a battle against _______.

A. the growth of deserts B. the disappearance of desert plants

C. natural changes  D. congenital climate

We can guess that Mauritania and Algeria belong to _______.

A. Asian countries 　　　　       B. American countries

C. European counties　　　 D. African countries

Choose the sentence which best gives the main idea of the passage.

A. The deserts of the world are always changing.

B. Man is to take measures to control the growth of the world’s deserts.

C. Deserts are lands of silence and space.

D. Deserts have grown at a fast pace in the past 10 years.

A desert is a beautiful land of silence and space. The sun shines, the wind blows, and time and space seem endless. Nothing is soft. The sand and rocks are hard, and many of the plants even have hard needles instead of leaves.

The size and location(分布) of the world’s deserts are always changing. Over millions of years, as climates change and mountains rise, new dry and wet areas develop. But within the last 100 yeas, deserts have been growing at a frightening speed. This is partly because of natural changes, but the greatest makers are humans.

Humans can make deserts, but humans can also prevent their growth. Algeria Mauritania is planting a similar wall around Nouakchott, the capital. Iran puts a thin covering of petroleum(石油) on sandy areas and plants trees. The oil keeps the water and small trees in the land, and men on motorcycles(摩托车) keep the sheep and goats away. The USSR and India are building long canals to bring water to desert areas.

In this passage, “needles” refers to _______.

A. small, thin pieces of steel.

B. long, thin pieces of branches.

C. small pointed growth on the stem(茎) of a plant.

D. small, thin pieces of sticks.

Which of the following is NOT true?

A. The greatest desert makers are humans.

B. There aren’t any living things in the deserts.

C. Deserts have been growing quickly.

D. The size of the deserts is always changing.

People in some countries are fighting a battle against _______.

A. the growth of deserts B. the disappearance of desert plants

C. natural changes  D. congenital climate

We can guess that Mauritania and Algeria belong to _______.

A. Asian countries 　　　　       B. American countries

C. European counties　　　 D. African countries

Choose the sentence which best gives the main idea of the passage.

A. The deserts of the world are always changing.

B. Man is to take measures to control the growth of the world’s deserts.

C. Deserts are lands of silence and space.

D. Deserts have grown at a fast pace in the past 10 years.