题目内容：

Stop. Listen! What do you hear? You may hear many different sounds. Some of those sounds may be noise. Noise is a loud or unwanted sound.

Noise can be caused by many kinds of machines, such as motorcycles, jet planes and farm tractors(拖拉机). Rock music is also noise.

What happens to people who live near noisy machines or use them over a period of time? Doctors have found that these people have trouble in sleeping. But, most important, constant(不断的) loud noise can cause a loss of hearing.

Scientists use a unit of measure called decibel(分贝) to measure the loudness of a sound. The sound of a quiet room, for example, measures 35 decibels. Talking measures between 40 and 65 decibels. Sounds from traffic and from some rock bands can measure over 120 decibels. Noise at this high level(层次) causes the great hearing loss.

1.According to the passage, noise is      .

A. any kind of soundB. a loud or unwanted sound

C. all sounds that you can hearD. terrible sound

2. A decibel is a      .

A. unit that measures soundB. kind of noise

C. machine that makes loud noiseD. person who hates sound

3.According to the passage, loud noise can      .

A. help people to sleep betterB. stop machines

C. cause a loss of hearing    D. kill people

4. We can conclude from the passage that      .

A. noise is a serious problemB. rock music isn’t noise

C. noise is only from trafficD. some people hate any sound

5.Study the diagram below.      would be the quietest.

Room	Noise Level
A	40~65 decibels
B	35 decibels
C	120 decibels
D	130 decibels

A. Room AB. Room BC. Room C D. Room D