问题 问答题 简答题

简述直线对于一个投影面的投影特性。

答案

参考答案:

当直线平行于投影面时,其投影反映真实长度;

当直线垂直于投影面时,其投影积聚成一点;

当直线倾斜于投影面时,其投影变短。

阅读理解

阅读短文,选择正确答案。

      One day I happened to meet an Englishman in the street and soon we began to talk. As I was talking about

how I was studying English, the foreigner seemed to be very surprised, gently shaking his head and saying "You

don't say!" I was puzzled, and I thought, "Perhaps this is not a right thing to talk about." So I said to him. "Well,

shall we talk about the Great Wall? Have you ever been there?"

      "Certainly! Everyone at home will laugh at me if I leave here without seeing it. The Great Wall is wonderful!"

"Yes, it is one of the wonders in the world. And people of many countries have come to visit it." As I went on

more about it, he stopped me again, "You don't say!"

      I couldn't help asking, "Why do you ask me not to talk about it?"

      "Well, I don't ask you to do so," he answered, greatly surprised.

      "Didn't you say 'You don't say'?" I asked again.

      Hearing this, the foreigner laughed loudly. He began to explain, " 'You don't say!' means 'Really?'. Perhaps

you know little about English idioms (习语)."

      Wow! How foolish I was! Since then I began to learn more English idioms.

1. The writer was puzzled (疑惑) because _________. [ ]

A. the foreigner has some trouble in understanding him

B. the writer himself didn't understand the meaning of "You don't say!"

C. the foreigner was not polite

2. What made the foreigner laugh? [ ]

A. The English idiom.

B. The writer's talking about the Great Wall.

C. The writer's question.

3. The story probably happened in _______. [ ]

A. China

B. America

C. England

4. The writer was puzzled ______ in the passage. [ ]

A. once

B. twice

C. three times

5. The English idiom "You don't say!" means "________". [ ]

A. Really?

B. You're right.

C. Thank you.

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