单项选择题：声波变密度测井时，通常由短源距接收探头接收的信号处理得到（）测井资料。A、声幅 B、

题型：单项选择题

阅读理解。

Plants are very important living things. Life could not go on if there were no plants. This is because

plants can make food from air, water and sunlight. Animals and men can't make food from air, water and

sunlight. Animals get their food by eating plants and other animals. Therefore, animals and men need plants

in order to live. This is the reason why we find so many plants around us. 　　

If you look carefully at the plants around you, you will find that there are many kinds of plants. Some

plants are large while others are small. Most plants are green. 　　

Some plants have many small leaves. Others have only a few. There are many kinds of leaves. Leaves

are of different shapes and colors. 　　

Leaves are also different in other ways. Some leaves have long thin parts at the end, we call them leaf

stalks, some have short leaf stalks, others even have no leaf stalks. The leaf edges are also different. Some

leaves have smooth (平滑) edges. Some have wave-shaped edges. Others have edges like the teeth of

a saw. (锯子)

1. Which of the following shows the right relation (关系) according to the first paragraph? [ ]

2. Plants are important because _____. 　[ ]

A. we need to eat plants every day

B. men can't live without plants

C. we can see so many plants around us

D. animals eat plants as their only food 　

3. We know from the passage that _____. 　　[ ]

A. all leaves have leaf stalks 　　

B. all leaves have smooth edges 　　

C. plants are different in shapes but have the same color 　　

D. leaves are different in shapes and colors 　　

4. The underline word "leaf stalks" in the last paragraph means _____. 　　[ ]

A. 叶边

B. 叶纹

C. 叶柄

D. 叶尖　　

5. The main idea of the passage is _____. 　　[ ]

A. how plants help men and animals 　　

B. plants are important and they are quite different 　　

C. plants are more important than air, water and sunlight 　　

D. why we find so many plants around us

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声波变密度测井时，通常由短源距接收探头接收的信号处理得到（）测井资料。A、声幅 B、