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 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.The half - life of C - 14 is about 25 ,000 years.【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碳的半衰期是25，000年，所以本题是未提及的，答案是C。

2、Please put up your bands if you have any questions. 【单选题】

A.raise

B.reach

C.wave

D.fold

正确答案:A

答案解析:putup和raise同义，举起；reach:伸（手等）；wave：挥手；fold:合拢。

3、Singing Alarms Could Save the BlindIf you cannot see, you may not be able to find your way out of a burning building and that could be fatal. A company in Leeds could change all that with directional sound alarms capable of guiding you to the exit. Sound Alert, a company run by the University of Leeds, is installing the alarms in a residential home for blind people in Sommerset and a resource centre for the blind in Columbia. The alarms produce a wide range of frequencies that enable the brain to determine where the sound is coming from. Deborah Withington of Sound Alert says that the alarms use most of the frequencies that can be heard by humans. "It\'s a burst of white noise that people say sounds like static on the radio," she says. "Its life-saving potential is great."She conducted an experiment in which people were filmed by thermal-imaging cameras trying to find their way out of a large smoke-filled room. It took them nearly four minutes to find the door without a sound alarm, but only 15 seconds with one. Withington studies how the brain processes sounds at the university. She says that the source of a wide band of frequencies can be pinpointed more easily than the source of a narrow band. Alarms basedon the same concept have already been installed on emergency vehicles. The alarms will also include rising or falling frequencies to indicate whether people should go up or down stairs. They were ______ with the aid of a large grant from British Nuclear Fuels. 【单选题】

A.developed

B.determined

C.discovered

D.delivered

正确答案:A

答案解析:主语they代指the alarms，后半句是说这种设备得到大笔资助。根据上下文，资助是了开发，所以应该选A。

4、AIDSAs a science writer, I don\'t have to wear emotional armor very often. Before I went to Zimbabwe for a visit, I had talked to other reporters who had spent time in Africa. All told me to get prepared for the orphans, many of whom had caught the AIDS virus from their mothers and the strong desire to make everything all right for them. Then again, nothing could have prepared me for the visit to creche(育婴堂) for AIDS orphans in Harare, where one sick, smiling four-year-old boy tried to keep up with the other kids playing ring-around-the-rosy but was so weak he kept falling to the floor, or meeting a 25-year-old unmarried girl who cared for her nephew ______ The boy who called his aunt "Mama" was too weak even to take the piece of banana I offered. Meanwhile photojournalist Karin Retief was visiting a room at the hospice (济贫院) where she had been told a particularly sweet orphan boy stayed. At first she did not see anyone on the bed and was about to say he must be elsewhere, when suddenly she spotted his tiny arm in the air, his body lost in the folds of the bedclothes. Recently Karin wrote to me that she had been able to keep our assignment from taking too great an emotional suffering at the time. " Only when I got back about a week later, could I moum the people I met", she continued. "I sat in church and wanted to ask the priest to pray for the people with AIDS in Zimbabwe and all over the world. Then all the people\'s faces, pain and suffering became so real, I could not get the words out. I broke down and cried and cried for them". 【单选题】

A.where she had been told a particularly sweet orphan boy stayed

B.who had spent time in Africa

C.Only when I got back about a week later

D.even though her only income was from growing and selling a few vegetables at the local market

E.was so weak he kept falling to the floor

F.while we were visiting the orphans

正确答案:D

答案解析:一个未婚女孩照顾她的侄子，尽管她的唯一收入来源是种菜，并在当地市场出售。符合语法要求，意思也完整。因此选D。

5、Meet Your Memory1. Memory is something that cannot be seen, touched or weighed. It is thought to be abstract. It is a set of skills rather than an object. Neither is there a single standard for judging a good or poor memory. There are a number of different ways in which a person may have a good memory.2. Memory is generally viewed as consisting of three stages: (1) acquisition refers to learning the material; (2) storage refers to keeping the material in the brain until it is needed; (3) retrieval (提取) refers to getting the material back out when it is needed:3. Memory consists of at least two different processes: short - term memory and long - term memory. Short - term memory has a limited capacity and a rapid forgetting rate. Its capacity can be increased by chunking (组成大块), or grouping separate bits of information into larger chunks. Long - term memory has an almost unlimited capacity.4. One measure of memory is recall, which requires you to produce information by searching the memory for it. In aided recall, you are given cues (提示) to help you produce the information. In free - recall learning you recall the material in any order. In serial learning you recall it in the order it was presented and in paired - associate learning you learn pairs of words so that when the first word is given you can recall the second word. A second measure of memory is recognition, in which you do not have to produce the information from memory, but must be able to identify it when it is presented to you. In a third measure of memory, relearning, the difference between how long it took to learn the material the first time and how long it takes to learn it again indicates how much you remember. Relearning is generally a more sensitive measure of memory than is recognition because relearning shows retention (保持) while recognition does not. Recognition is generally a more sensitive measure than recall.Paragraph 3 ______【单选题】

A.Why do we forget things?

B.How do we measure memory?

C.What are the stages memory consists of?

D.What is the difference between short - term memory and long - term memory?

E.What is memory?

F.Who may have a poor memory?

正确答案:D

答案解析:本题难度不大，主旨句比较明显，是文章第三段的第一句，谈到记忆力包括两种不同的过程，短期记忆和长期记忆，回来看选项，D项What\'s the difference between short - term memory and long - term memory?是对本段主旨句的近义替换，是答案。