问题 单项选择题

在效率相同的情况下,要使两台泵相似,必须具备()的条件。

A、几何相似、运动相似、功率相似

B、几何相似、功率相似、动力相似

C、功率相似、运动相似、动力相似

D、几何相似、运动相似、动力相似

答案

参考答案:D

阅读理解

阅读理解。

     Hi, there! I’m Crystal Collins, and I’m very happy to share some time with you. So, you want to keep

fit, huh? Well, you surely came to the right place. Together we can keep fit and healthy, and succeed in

doing that. It’s easy. Everybody can do it, you hear? Just remember the five golden rules.

     Number one. Always wear comfortable clothes when you are exercising. You need to feel comfortable and relaxed.

     Number two. You should always do some warming-up exercises first. Get your body ready for the

real thing.

     Number three. Never try to do too much exercise too soon. Take it nice and easy now, you hear?

There’s no rush about this.

     Number four. Don’t forget to relax for about five minutes when you’ve finished your exercise. You

need to rest a little bit after you’ve been exercising.

     And here is golden rule number five. Stop at once if you feel any pain in your neck, head or any part of your body.

1. Crystal Collins may most probably be _____.

A. a teacher

B. a doctor

C. a policeman

D. a scientist

2. Crystal Collins may most probably say this _____.

A. before the exercise starts

B. when the exercise is over

C. during the exercise

D. as soon as the exercise has started

3. What does the underlined words “Take it nice and easy” in Paragraph 4 mean?

A. Don’t be nervous.B. Exercise should be beautiful.

C. Have a good rest.D. don't exercise too tiredly .

4. Which of the following is NOT true about exercising?

A. You should do some warming-up exercises before the real thing.

B. You should wear comfortable clothes.

C. You should rest for a while when you are doing warming-up exercises.

D. You should stop if you feel any pain in your body.

问答题 简答题