问题 单项选择题

超声波:是人耳听不到的声波。按照这个定义,下列说法正确的是( )。

A.低于20HZ的声波,入耳听不到,是超声波

B.高于20000HZ的声波,人耳听不到,是超声波

C.电铃的铃声约800HZ,人们听得很清楚;将电铃放在抽真空的玻璃罩内,电铃工作时,人们听不到铃声。这时,800HZ的声波转化为超声波

D.“B超”是先进的医疗影象技术,它发射超声波。有人认为,虽然人耳听不见超声波,但人眼却可以看见

答案

参考答案:B

解析: 低于20HZ的声波是次声波,A项错误。声音的传播要靠空气作为介质,所以C项中“人们听不到铃声”的原因是真空。超声波无法看到,D错误。

阅读理解

任务型阅读。

     阅读下面的短文,请根据短文后的要求答题(请注意问题后的词数要求)。

     There's a lot of discussion these days about fit kids. Being fit is a

way of saying a personeats well, gets a lot of physical activity (exercise) ,

and has ahealthy weight. If you're fit, your body works well, feelsgood,

and can do all the things you want to do.

      Here are four rules to live by, if you're a kid who wants tobe fit.

       1. Eat a variety of foods, especially fruits and vegetables.

      You may have a favorite food, but the best choice is to eat

a variety.If you eat different foods, you're more likely to get

the nutrients your body needs. Taste new foods and old ones

you haven't tried for a while.

         2. Drink water and milk most often.

      When you're really thirsty, cold water is the No. 1 thirst-

quencher. And there's a reason your school cafeteria offers

cartons of milk. Kids need calcium to grow strong bones, and

milk is a great source of this mineral.

         3. Listen to your body.

    What does it feel like to be full? When you're eating,

notice how your body feels and when your stomach feels

comfortably full. Sometimes, people eat too much because they

don't notice when they need to stop eating. Eating too much can

make you feel uncomfortable, and over a period of time, it can

lead to _____.

        4. Be active.

      One job you have as a kid-and it's a fun one-is that you

get to figure out which activities you like best. Not everyone

loves baseball or soccer. Maybe your passion is karate, or

kickball, or dancing. Ask your parents to help you do your

favorite activities regularly. Find ways to be active every day.

1. What is the best title of this passage? (Please answer   within 10 words. )

_____________________________________________________________

2. Which sentence in the passage can be replaced by thefollowing one?

     You might keep yourself healthy and vivid as a result of avariety of foods.

_____________________________________________________________

3. Please fill in the blank in the 5th paragraph with properwords or phrases to

    complete the sentence. (Please answerwithin 10 words. )

______________________________________________________________

4. Which of the four rules do you think is the most important for you? Why?  

   (Please answer within 30 words. )

_______________________________________________________________

5. Translate the underlined sentence in the last paragraph intoChinese.

________________________________________________________________

单项选择题