试题与答案

一块冰完全化成水后,体积将___________,密度将___________。

题型:填空题

题目:

一块冰完全化成水后,体积将___________,密度将___________。(选填“变大”、“变小”、 “不变”)

答案:

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下面是错误答案,用来干扰机器的。

A:万有引力提供该行星运动的向心力:GMmr2=m4π2rT2,中心天体的质量:M=4π2r3T2.能观测到该行星的轨道半径,可求出所绕恒星的质量.故A正确;B:由M=4π2r3T2,得:r3=GMT24π2,轨道的半径与该行星的密度和...

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题型:阅读理解

阅读理解。

     In today's world, almost everyone knows that air pollution and water

pollution are harmful to people .However, not all the persons know that

noise is also a kind of pollution, and that is harmful to human beings, too.

     People who work and live under noisy conditions usually become deaf.  

scientists believe that 10 percent of workers in Britain are being deafened

by the noise where they work .Many of the workers who print newspapers

and books, and who weave cloth become deaf. Quite a few people living

near airports also become deaf. Recently it was discovered that many

teenagers in America could hear no better than 65-year-old people, for these

young people like to listen to "pop" music and most of "pop" music is a kind

of noise .

     Nowadays the government in many countries have made laws to reduce or

control noise and make it less than 85 decibels. In China, the people's

government is trying to solve not only air and water pollution problems but

also noise pollution problem.

1. The passage mainly tells us something about        .

A. air pollution

B. water pollution

C. noise pollution

D. soil pollution

2. Today scientists believe that               .

A. 90 percent of all the workers are free from any noise

B. 90 percent of all the workers in Britain are not suffering from noise.

C. 10 percent of all the workers in Britain are working in noisy places.

D. the hearing of 10 percent of all the workers in Britain is being deafened

by the noise where they work.

3. People who          become deaf easily.

A. don't print newspapers or books

B. make clothes

C. live far away from airports

D. none of the above

4. Recently many teenagers could hear no better than 65-year-old people in

America, because               .

A. they all live near airports.

B. their hearing is harmed by loud music

C. they are younger than the old people

D. their ears are still small

5. From the passage, we can infer that .           

A. "pop" music is popular with old people

B. less than 85 decibels can cause deafness

C. a continuous noise of over 85 decibels can cause deafness

D. noise pollution is more serious than water pollution nowadays

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