2020年职称英语考试《理工类》考试共65题，分为单选题和多选题和判断题和计算题和简答题和不定项。小编每天为您准备了5道每日一练题目（附答案解析），一步一步陪你备考，每一次练习的成功，都会淋漓尽致的反映在分数上。一起加油前行。

1、Radiocarbon Dating
Nowadays scientists can answer many questions about the past through a technique called radiocarbon (放射性碳), or carbon - 14 dating. One key to understanding how and why something happened is to discover when it happened.
Radiocarbon dating was developed in the late 1940s by physicist Willard F. Libby at the University of Chicago. An atom of ordinary carbon, called carbon -12, has six protons (质子) and six neutrons (中子) in its nucleus (原子核). Carbon - 14, or C - 14, is a radioactive, unstable form of carbon that has two extra neutrons. It returns to a more stable form of carbon through a process called decay (衰减). This process involves the loss of the extra neutrons and energy from the nucleus.
In Libby's radiocarbon dating technique, the weak radioactive emissions(放射)from this decay process are counted by instruments such as a radiation detector and counter. The decay rate is used to determine the proportion of C -14 atoms in the sample being dated.
Carbon - 14 is produced in the Earth's atmosphere when nitrogen(氮) - 14, or N - 14, interacts with cosmic rays (宇宙射线). Scientists believe since the Earth was formed, the amount of nitrogen in the atmosphere has remained constant. Consequently, C -14 formation is thought to occur at a constant rate. Now the ratio of C -14 to other carbon atoms in the atmosphere is known. Most scientists agree that this ratio is useful for dating items back to at least 50,000 years.
All life on Earth is made of organic molecules (分子) that contain carbon atoms coming from the atmosphere. So all living things have about the same ratio of C -14 atoms to other carbon atoms in their tissues (组织). Once an organism (有机体) dies it stops taking in carbon in any form, and the C -14 already present begins to decay. Over time the amount of C - 14 in the material decreases and the ratio of C - 14 to other carbon atoms goes down. In terms of radiocarbon dating, the fewer C -14 atoms in a sample, the older that sample is.
When an organism dies, the C -14 in it begins to decay.
【单选题】

A.Right

B.Wrong

C.Not mentioned

正确答案:A

答案解析:本题有一定难度，但答案依据比较明显。带着题干信息词回文章定位，文章最后一段第三句：Once an organism dies it stops taking in carbon in any form，and the C - 14 already present begins to decay谈到一旦有机体死亡，就停止吸收任何形式的碳，现有的碳14也会逐渐衰变，题干是其近义解释，所以正确，答案是A。

2、Science Fiction
1 Amongst the most popular books being written today are those that are usually classified as
science fiction. Hundreds of titles are published every year and are read by all kinds of people.
Furthermore, some of the most successful films of recent years have been based on science fiction stories.
2 It is often thought that science fiction is a fairly new development in literature, but its ancestors can be found in books written hundreds of years ago. These books were often concerned with the presentation of some forms of ideal society, a theme that is still often found in modern stories.
3 Most of the classics of science fiction, however, have been written within the last hundred years. Books by writers such as Jules Verve and H. G Wells, to mention just two well known authors, have been translated into many languages.
4 Modern science fiction writers don't write about men from Mars or space adventure stories. They are more interested in predicting the results of technical developments on society and the human mind; or in imagining future worlds that are a reflection of the world that we live in now. Because of this their writing has obvious political undertones (涵义).
5 In an age where science fact frequently overtakes (超过) science fiction, the writers may find it difficult to keep ahead of scientific advances. Those who are sufficiently clear-sighted to see the way we are going, however, may provide a valuable lesson on how to deal with the problems which society will inevitably face as it tries to master its new technology.
Paragraph 3____
【单选题】

A.A Fairly New Development

B.Classics of Science Fiction

C.Difficulty in Keeping ahead of Scientific Advances

D.Origins of Science Fiction

E.Themes of Modern Science Fiction

F.SuccessfulFilms

正确答案:B

答案解析:该段主要是在介绍经典科幻小说，其实该段第1句就已经出现了classics这个词，所以选项B是正确答案。

3、An Intelligent Car
Driving needs sharp eyes, keen ears, quick brain, and coordination between hands and the brain. Many human drivers have all. these and can control a fast-moving car. But how does an intelligent car control itself ?
There is a virtual driver in the smart car. This virtual driver has "eyes," "brains", "hands" and "feet", too. The mini-cameras on each side of the car are his "eyes," which observe the road and conditions ahead of it. They watch the traffic to the car's left and right. There is also a highly automatic driving system in the car. It is the built-in computer, which is the virtual driver's "brain". His "brain" calculates the speeds of other moving cars near it and analyzes their positions. Basing on this information, it chooses the right line for the intelligent cars, and gives instructions to the "hands" and "feets" to act accordingly. In this way, the virtual driver controls his car.
What is the virtual driver's best advantage? He reacts rapidly. The mini-cameras are sending images continuously to the "brain". It ______ the processing of the images within 100 milliseconds. However, the world's best driver at least needs one second to react. Besides, when he takes action, he needs one more second.
The virtual driver is really wonderful. He can reduce the accident rate. considerably on expressway. In this case, can we let him have the wheel at any time and in any place? Experts warn that we cannot do that just yet. His ability to recognize things is still limited. He can now only drive an intelligent car on expressways.
【单选题】

A.selects

B.completes

C.uses

D.tests

正确答案:B

答案解析:空白所在的句子说“它在100毫秒的时间里……图像的处理”，根据该句内容判断B（完成）是答案。

4、Shopping at Second - hand Clothing Stores
When 33 year old Pete Barth was in college, shopping at second hand clothing stores was just something he did- "like changing the tires on his car." He looked at his budget and decided he could save a lot of money by shopping for clothes at thrift shops.
"Even new clothes are fairly disposable (用后即丢掉的) and wear out after a couple of years," Barth said. "In thrift shops, you can find some great stuff whose quality is better than new clothes."
Since then, Barth, who works at a Goodwill thrift shop in the US state of Florida, has found that there are all kinds of reasons for shopping for second - hand clothing. Some people, like him, shop to save money. Some shop for a crazy - looking shirt. And some shop as a mean conserving energy and helping the environment.
Pat Akins, an accountant at a Florida Salvation Army (SA) (救世军) thrift shop, said that, for her, shopping at thrift shops is a way to help the environment.
"When my daughter was little, we looked at it as recycling," Akins said. "Also, why pay 30 dollars for a new coat when you can get another one for a lot less?"
Akins said that the SA has shops all over the US- "some as big as department stores. All of the clothes are donated (捐赠), and when they have a surplus (盈余), they'll have" stuff a bag" specials, where customers can fill a grocery sack with clothes for only 5 or 10 dollars.
Julia Slocum, 22, points out, however, that the huge amount of second - hand clothing in the US is the result of American wastefulness.
"I'd say that second - hand stores are the result of our wasteful, materialistic culture," said Slocum, who works for a pro - conservation organization, the center of a New American Dream. "Thrift shops prevent that waste from going to landfills (垃圾填埋场). They give clothing a second life, provide cheaper clothing for those who can't afford to buy new ones and generate (创造) income for charities. They also provide a way for the wealthy and middle classes to shed (摆脱) the guilt for their level of consumption.
Which statement about Barth is NOT true? ______【单选题】

A.He is 33 years old now.

B.He works at a Goodwill thrift shop.

C.He works at a Salvation Army thrift shop.

D.He was a college student many years ago.

正确答案:C

答案解析:本题难度较大，需要认真阅读文章，做出判断。认真阅读文章前三段。第一段第一句谈到了作者大学期间经常逛二手服装店，第三段第一句话谈到了作者在Goodwill旧货店工作，可以推断A，B，D项正确，所以答案是C。

5、Seeing Red Means Danger Ahead
The color red often means danger and by paying attention, accidents can be prevented. In the future, the color red also may help prevent danger at construction sites. Thanks to new work by engineers, bridge supports or ______ kinds of materials could one day contain a color switching material. It will turn red before a structure collapses or falls apart.
The secret behind the color switching material is a particular type of molecule. A molecule is a group of atoms held together by chemical bonds. Molecules come at all shapes and sizes, and make up everything. You can see, touch or feel. How a molecule behaves depends on what kinds of atoms it contains, and how they're held together.
When a polymer (聚合物) containing a color switching molecule called a mechanophore (机械响应性聚合物) which is about to break, it produce a color. When a polymer with mechanophore molecules becomes "injured" or weak, one of the mechanophore bonds breaks and the material turns red. "It's a really simple detection method. "says Nancy Sottos, one of the scientists who worked on the project. Sottos and her team tested the color switching polymers in their lab. The test results proved encouraging.
There is a way to get rid of the color light when a bright light is shone on the mechanophore.
The broken bond is fixed and the red color disappears. This "self-healing" may be a problem for engineers. They need to use the color changer in big construction projects that will be outside in sunlight. And sunlight will make the mechanophore's warming system useless. Sottos and her fellow scientists still have a lot of work to do before the color switching molecules can be used outside the lab.
【单选题】

A.other

B.another

C.the other

D.others

正确答案:A

答案解析:bridge supports意为桥梁支柱，后用or连接，是指与桥梁支柱同样的事物，所以插入语部分应该指“其他建筑材料”。another后跟名词单数。the other使用时一般在前面有对比参照物。others本身就是指代名词，后不需要再有词语。other指代其他的，后可跟名词。