问题 单项选择题

在三相交流异步电动机的定子上布置有()的三相绕组。

A、结构相同,空间位置互差90°电角度

B、结构相同,空间位置互差120°电角度

C、结构不同,空间位置互差180°电角度

D、结构不同,空间位置互差120°电角度

答案

参考答案:B

阅读理解

阅读理解。

     Did you know that birds could be "property owners", too? In spring, the male robin (知更鸟) looks for a

place to build a nest. A tree neara green lawn (草坪) that has many worms (虫子) suits him best. When he

finds the right place, he sings loudly. He tells other birds that this place is his property.

      At the same time, other birds are choosing places for their nests. A robin does not mind if swallows nest

nearby because swallows eat insects. They leave his worms alone. But other robins are different. They would

eat the worm supply he needs for his own family.

      When another male robin comes near, the robin owner sings to wam him away. The property owner looks

cross and fierce (凶猛的). He raises his head feathers and holds his tail high. If the owner cannot frighten

away the new robin, he attacks. The two fight until one is the winner. The new bird often gives up and flies

away. So the first bird has defended his property. He now has the right to build a nest in the place.

1. The male robin looks for a place to build a nest _____ .

A. near swallows

B. near other male robins

C. near a lawn with worms

D. in the woods

2. The story does not say so, but it makes you think that robins _____.

A. drive away all the other birds

B. do not care where they build their nests

C. are careful when choosing a place to nest

D. are not afraid of other birds

3. On the whole, this story is about _____.

A. what robins eat

B. robins finding a nesting place

C. robins finding friends

D. how robins live with swallows

4. Why does the male robin raise his head feathers and hold his tail high?

A. He wants to drive away another male robin.

B. He is getting ready to hunt for worms.

C. He is too warm.

D. He wants to look more beautiful.

5. In this passage the word "cross" means ______.

A. angry

B. worried

C. happy

D. around

单项选择题