People regularly exposed to levels over 80 decibels are risking their health.
人们经常接触噪音超过80分贝时，健康就会受到影响。

It damages the hearing and causes deafness.
损害听力或引起耳聋。
It causes inflammation [9infl[`meiF[n] of the living of the stomach and the brain.

引起胃壁和大脑发炎。
It makes small blood vessels constrict [k[n`strikt].
使细血管收缩。
It cuts down the blood supply to the heart.
降低对心脏的供血。
It dilates [dai`leit] the retina [`retin[] of the eye, causing color blindness and inaccurate vision.
扩大眼睛的视网膜，从而引起色盲和视力模糊。

The normal range of human hearing is between the frequencies of 20 and 20,000 Hz. There is a whole area of sound beyond this range, known as ultrasonics (超声波), which we cannot hear.
人耳承受的正常范围是20到20，000赫兹频之间，超过这个音区的是超声波，人耳听不见。

***** Proverb *****
A short cut is often a wrong cut. 欲速则不达。
All time is no time when it is past. 机不可失，时不再来。

Unit Humor

No Problem

　　A man called his doctor's office for an appointment. "I'm sorry," said the receptionist (接待员), "we can't fit (安排) you in for at least two weeks."
　　"But I could be dead by then!"
　　"No problem. Let your wife tell us then, and we will cancel (删去) the appointment."