Stop .Listen!What do you hear You may hear many different sounds .Some of those sounds may be nouse .Noise is a loud or unwanted sound .
Noise can be caused by many kinds of machines ,such as motorcycles ,jet planes ,farm tractors （拖拉机）.rock music is also noise.
What happens 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 quier 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 great hearing loss.
（）1.According to the passage ,noise is（）
A.any kind of sound
B.a loud or unwanted sound
C.all sounds that you can hear
D.terrible sound
（）2.According to the passage ,loud noise can（）
A.help people to sleep better
B.stop machines
C.cause a loss of hearing
D.kill people