2021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.Radiocarbon is reliable in dating an object back to at least 50,000 years.【单选题】

A.Right

B.Wrong

C.Not mentioned

正确答案:A

答案解析:本题难度不大，答案依据比较明显，主要答案依据在文章第四段最后一句：Most scientists agree that this ratio is useful for dating items back to at least 50,000 years谈到科学家相信，这样的比率对于测定5万多年前的物体有用，题干是其近义解释，所以正确，答案是A。

2、How to Be a Successful BusinesspersonHave you ever wondered why some people are successful in business and others are not? Here\'s a story about one successful businessperson. He started out washing dishes and today he owns 168 restaurants.Zubair Kazi was born in Bhatkal, a small town in southwest India. His dream was to be an airplane pilot, and when he was 16 years old, he learned to fly a small plane.At the age of 23 and with just a little money in his pocket, Mr. Kazi moved to the United States. He hoped to get a job in the airplane industry in California. Instead, he ended up working for a company that rented cars.While Mr. Kazi was working at the car rental(租赁的) company, he frequently ate at a nearby KFC restaurant. To save money on food, he decided to get a job with KFC. For two months, he worked as a cook\'s assistant. His job was to clean the kitchen and help the cook. "I didn\'t like it," Mr. Kazi says, "but I always did the best I could."One day, Mr. Kazi\'s two co - workers failed to come to work. That day, Mr. Kazi did the work of all three people in the kitchen. This really impressed the owners of the restaurant.A few months later, the owners needed a manager for a new restaurant. They gave the job to Mr. Kazi. He worked hard as the manager and soon the restaurant was making a profit.A few years later, Mr. Kazi heard about a restaurant that was losing money. The restaurant was dirty inside and the food was terrible. Mr. Kazi borrowed money from a bank and bought the restaurant. For the first six months, Mr. Kazi worked in the restaurant from 8 a. m. to 10 p. m. , seven days a week. He and his wife cleaned up the restaurant, remodeled the front of the building, and improved the cooking. They also tried hard to please the customers. If someone had to wait more than ten minutes for their food, Mrs. Kazi gave them a free soda. Before long the restaurant was making a profit.A year later, Mr. Kazi sold his restaurant for a profit. With the money he earned, he bought three more restaurants that were losing money. Again, he cleaned them up, improved the food, and retrained the employees. Before long these restaurants were making a profit, too.Today Mr. Kazi owns 168 restaurants, but he isn\'t planning to stop there. He\'s looking for more poorly managed restaurants to buy. "I love it when I go to buy a restaurant and find it\'s a mess," Mr. Kazi says. "The only way it can go is up. "Mr. Kazi became the manager of a new restaurant because_____.【单选题】

A.his co -workers praised him

B.he was a good cook

C.he worked very hard

D.he knew how to run a restaurant

正确答案:C

答案解析:本题难度也不大，也是送分题目，答案依据是：That day，Mr. Kazi did the work of all three people in the kitchen. This really impressed the owners of the restaurant.

3、Walking to Exercise the BrainDo you think sitting and studying all the time will improve students grades? Think again. Getting some exercise may help, too.New research with older people suggests that taking regular walks helps them pay attention better than if they didn\'t exercise.Previous research had shown that mice learn, remember and pay attention better after a few weeks of working out on a running wheel. Mice that exercise have greater blood flow to the brain than those who don\'t. Their brain cells also make more connections.Neuroscientists (神经科学家) from the University of Illinois at Urbana Champaign wanted to find out if the same thing is true for people. First, they measured the physical fitness of 41 adults, ages 58 to 77, after each person walked I mile. Then, participants looked at arrows on a computer screen and had to use computer keys to show which way one particular arrow was pointing.Adults who were physically fit were faster at the arrow task, and their answers were just as accurate as their less - fit peers, the researchers found. The fitter participants also had more blood flow to a part of their brain responsible for paying attention and making decisions.In a second study, 15 elderly people who completed a 6 - month aerobic - training (有氧运动) course were faster at attention tasks compared with 14 seniors who just did stretching and toning (韵律操) exercises for the same amount of time.So, even going for a walk every 2 or 3 days for just 10 to 45 minutes can help. That should be good news for the elderly.The effects of exercising on the brains of younger people haven\'t been studied yet. Still, it can\'t hurt to take occasional breaks and go for a walk or run around with friends. Whatever you do, though, don\'t try to read and walk at the same time. You could end up hurting yourself!The first study on 41 elderly people found ______.【单选题】

A.the less - fit participants did arrow tasks faster

B.the fitter participants did arrow tasks faster

C.the less - fit participants gave more accurate answers

D.the fitter participants gave more accurate answers

正确答案:B

答案解析:本题有一定难度，需要认真阅读文章。答案依据在文章第五段。带着题干信息词回到文章定位。第五段第一句谈到，研究者发现身体健康的成年人完成箭头测试的速度更快，回来看选项，很明显，B是近义解释，是答案。

4、Eventually, she got a job and moved to London.【单选题】

A.Certainly

B.Luckily

C.Naturally

D.Finally

正确答案:D

答案解析:最终，她找到工作搬到伦敦去了。本题难度不大，是送分题，干扰项干扰不强，eventually和finally都指“最后，最终”，不难找到答案D。

5、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 _____ 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 rejects. 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.need

B.time

C.fact

D.case

正确答案:D

答案解析:本题有一定难度，考查in case的用法，in case指“以免，以防”，文章此处是说“……以免这种病毒卷土重来”，答案是D。