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。小编为您整理历年真题5道练习题，附答案解析，供您备考练习。

1、Radiocarbon DatingNowadays 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.Radar is used to determine the characteristics of radiocarbon.【单选题】

A.Right

B.Wrong

C.Not mentioned

正确答案:C

答案解析:本题有较大难度，答案依据不明显，需要通读全文作出判断。通读全文后可以发现文章并未提及使用雷达来进行放射性碳测定，所以本题是未提及的，答案是C。

2、One Good Reason to Let Smallpox LiveIt\'s now a fair bet that we will never see the total extinction (灭绝) of the smallpox (天花) virus. When smallpox was completely got rid of in the world, scientists wanted to destroy the killer virus in the last two labs, one in the US and one in Russia. They asked: If smallpox has truly gone from the planet, what point was there in keeping these reserves?In reality, of course, it was naive to imagine that everyone would let go of such a powerful potential weapon. Undoubtedly several nations still have a few vials (小药瓶). And the last "official" stocks of live Virus bred mistrust of the US and Russia, for no obvious gain.Now American researchers have found an animal model of the human disease, opening the way for tests on new treatments and vaccines(疫苗). So once again there\'s a good reason to the virus, just in keep the disease puts in a reappearance.How do we case with the mistrust of the US and Russia? deal. Keep the virus Simple international support in a well - guarded UN laboratory that\'s open to all countries. The US will object, of course, just as it with a multilateral (多边的) approach to just about everything. But it doesn\'t mean the idea is _____. If the virus is useful, then let\'s wrong it the servant of all humanity make not just a part of it.【单选题】

A.adopts

B.rejects

C.suggests

D.introduces

正确答案:B

答案解析:本题有一定难度，考查词义辨析。本题可以借助语法知识来确定答案。句子的前后两部分用as连接，表明前后两句话的意思相近，前半句中出现object 一词，那么后面应用object的近义词，都是“反对”的意思，答案是B。

3、The courageous hay has been the subject of massive media coverage.【单选题】

A.extensive

B.continuous

C.instant

D.quick

正确答案:A

答案解析:这个勇敢的男孩成为了媒体大幅报道的对象。本题难度不大，干扰项干扰不强。m assive和extensive都可指“大量的”，其他项和答案意义差异较大，最佳答案是A。

4、Lakes, Too, Feel Global WarmingThere\'s no doubt, In the last few decades, the average temperature on Earth has been higher than it has been in hundreds of years. Around the world, people are starting to measure the effects of global warming and trying to figure out what to do about it.Scientist recently used satellites to study the temperatures of lakes around the world and they found that lakes are heating up. Between 1985 and 2009, satellites recorded the night time temperatures of the surfaces of 167 lakes. During those 24 years, the lakes got warmer by an average of about 0.045 degree Celsius per year.In some places, lakes have been warming by as much as 0.10 degree Celsius per year. At that rate, a lake may warm by a full degree Celsius in just 10 years. That difference may seem small you might not even notice it in your bath. But in a lake, slightly warmer temperatures could mean more algae (水藻) and algae can make the lake poisonous to fish.The study shows that in some regions, lakes are warming faster than the air around them. This is important because scientists often use measurements of air temperature to study how Earth is warming. By using lake temperatures as well, scientists can get a better picture of global warming. The scientists say data on lakes give scientists a new way to measure the impact of climate change around the world.That\'s going to be useful, since no matter the country is too big or too small can\'t ignore climate changes. Scientists aren\'t the only ones concerned. Everyone who lives on Earth is going to be affected by the rapid warming of the planet. Many world leaders believe we might be able to do something about it, especially by reducing the amount of greenhouse(温室) gases we put into the air.That\'s why the United Nations started the Framework Convention on Climate Change, or UNFCCC. Every year the convention meets, and representatives from countries around the world gather to talk about climate change and discuss global solutions to the challenges of a warming world.Lakes seem to be warming faster in Asia.【单选题】

A.Right

B.Wrong

C.Not mentioned

正确答案:C

答案解析:本题难度较大，答案依据不明显，需要通读全文。通读全文可以发现，文章并没有提到亚洲地区的湖水升温更快些，本题是没有提及的，答案是C。

5、Mary rarely speaks to Susan.【单选题】

A.slowly

B.seldom

C.weakly

D.constantly

正确答案:B

答案解析:玛丽很少和苏珊说话。本题难度不大，干扰项干扰不强。rarely和seldom都可指“很少地”，其他项和答案意义差异较大，最佳答案是B。