问题 问答题 简答题

请简述噪声控制方法.

答案

参考答案:

噪声形成干扰的环节是:声源一传播_接收者。因此噪声控制离不开从这三个环节

着手,即①降低声源的声音强度;②在传播途径中加以阻隔或吸收使之衰减;③对可能受噪声伤害的人实施个体防护。其中第③个环节,只应用在劳动生产的现场,常是前两个环节不能充分有效时,“追不得已”而为之的。

(1)降低声源的声音强度。改进机器设备的设计以降低运行噪声,如重视减振、润滑、选用摩擦与撞击声小的零部件材料,选用低噪声工艺流程等。

(2)控制噪声传播途径这是三个环节中约束相对少、较易于施行因而采用较普遍的方法。

(3)对工作人员实施个体防护给工作人员佩带耳塞、耳罩、头盔等

阅读理解

On June 26, 2000, two scientists, called Francis Collins and Craig Venter, told the world that they could read the whole “map” of the human body: DNA. DNA is something that everybody has, and it tells the body what to do. DNA is the reason that we look like our mother and father, because we get some of their DNA to make our own.

People have been trying to understand the human body for a long time. In 1860, Gregor Mendel discovered a special reason why we look the same as other people in our family. It is because of small things named “genes” in our body. In 1953, James Watson and Francis Crick made another discovery and found out that those small parts are real messages written in the DNA with a special language.

In 1961, Marshall Nirenberg and Johann Matthaci found a message in DNA showing how DNA tells the cell(细胞)to build its parts. Scientists have now found all the words in the DNA map, but we still do not understand what they all do. By understanding what just one “word”   means, we can help save more people from several illnesses.

Most people hope that this will help make better medicine and help sick people. Other people worry that when people begin to know more words and find out lots of other information, we might use it in a wrong way, just to make people more attractive, or stop sick people from getting jobs. Man would have to meet a lot of trouble if DNA technic wasn’t limited(限制)in use.

小题1:When did we first know why we look like other people m our family?

A.In 1860

B.In 1953

C.In 1961

D.In 2000小题2:What does the underlined word “ genes” mean?

A. The “map” of DNA.                B. A special language.

C. Small parts of DNA.                D. DNA

小题3:What did the two scientists first discover in 1961 ?

A. The “map” of DNA.               B. A new illness.

C. The language of DNA.              D. A message of DNA.

小题4:What can we do if we understand some “ words” of the language inside the body

A.Make people get new jobs.

B.Make medicine for illnesses.

C.Make maps of human.

D.Make people less attractive.小题5:What do people think about this work’?

A.It can cause good or bad results.

B.It can cause only good results.

C.It can cause good results but won’t work.

D.It can cause only bad results.

多项选择题