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

     Noise can be caused by many kinds of machines, such as motorcycles, jet planes, tractors and so on. And, to some people, rock bands (摇滚乐队) are also noise.

     What happens to people who live near noisy machines or use them over a period of time? Doctors find 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 (单位) of measure called a 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 to 65 decibels. Sounds from traffic and from some rock bands can measure over 120 decibels. Noise at this high level causes the greatest hearing loss.

     49.  From the passage, we know noise is _______.

          A. wanted sound                 B. loud or unwanted sound

          C. all sounds that you can hear      D. comfortable sound

     50. A "decibel" is a _______.

          A. unit that measures sound

          B. kind of noise

          C. machine that makes very loud noise

          D. person who hates noise

     51.  According to the passage, loud noise can_______.

          A. help people sleep better       B. stop machines

          C. cause a loss of hearing        D. kill people

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

Noise call be caused by many kinds of machines，such as motor cycles，jet planes and tractors．And，to some people，rock bands can also brining noise．

What happens to people who live near noisy machines or use them for a long time? Doctors find that these people have trouble sleeping．But，most importantly，constant（持续的）loud noise can cause a loss of hearing．

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

1．Noise can be caused by all the following except ________ according to the passage．

A．rock bands           B．tractors                C．jet planes                D．computers

2．“Decibel” is a ________．

A．unit that measures sound                          B．kind of noise

C．machines that makes very loud noise            D．person who hates noise

3．According to the passage，loud noise can ________．

A．help people sleep better                             B．make people work longer

C．make people deaf                                       D．make people happy and excited

4．Which of the following is TRUE?

A．Going to a concert is bad for our cars．

B．Not all sounds are noise．

C．The loudest noise comes from traffic and rock bands．

5．What's the main idea of this passage?

A．Noise pollution can be a serious problem．   B．Rock bands are noisy．

C．The way to measure noise．                        D．How to stop noise pollution．

Stop! Listen! What do you hear? You may hear many different sounds. Some of those sounds may be noisy. Noise is loud and unwanted sound.
Noise can be caused by many kinds of machines, such as motorcycles, jet planes, tractors and so on. And, to some people, rock bands are also noise.
What happened to people who live near noisy machines or use them over a period of time? Doctors find that these people have trouble in sleeping, But, most important, constant loud noise can cause a loss of hearing.
Scientists use a unit of measure called a decibel 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 causes the greatest hearing loss.
【小题1】 From the article we know noise is ___________.
wanted sound               B. loud and unwanted sound
C.  all sounds that you can hear    D. comfortable sound
【小题2】  A “decibel” is a _________

Stop and 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 (喷气式飞机), farm tractors, and power motors. And, to some people, rock music is also a 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. And most importantly, constant (连续的) loud noise can cause loss of hearing.
Scientists use a unit of measure called a 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 measure over 120 decibels. Noise at such high level causes the greatest hearing loss.
根据短文内容，判断下列句子是否正确，对的涂（A），错的涂（B）。(10分)
【小题1】According to the passage, noise is all sounds that you can hear.
【小题2】A “decibel” is a machine that makes loud noise.
【小题3】Loud noise can help people sleep better.
【小题4】Not all people think that rock music is a noise.
【小题5】We can infer (推断) from the passage that noise is a serious problem.