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 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.Nowadays many scientists depend on radiocarbon for dating age - old objects.【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一段第一段：Now-adays scientists can answer many questions about the past through a technique called radiocarbon，or carbon - 14 dating，谈到现在科学家可以通过一种叫做放射性碳定年法来解读过去，题干是其近义解释，所以正确，答案是A。

2、An Intelligent CarDriving needs sharp eyes, keen ears, quick brain, and coordination between hands and the brain. Many human drivers have all.______ 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 completes 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.these

B.them

C.this

D.that

正确答案:A

答案解析:根据all的习惯搭配：all＋指示代词，因此首先排除B（人称代词）。结合前句内容，空白处的代词应该指代前句中提到的“敏锐的眼睛和耳朵、反应迅速的大脑、手和大脑之间的协调”，因此应该选择指代复数的指示代词these。

3、Don\'t Rely on Plankton to Save the PlanetEncouraging plankton growth in the ocean has been touted by some as a promising way to remove carbon dioxide from the atmosphere. Its opponents fear that will damage the marine ecosystem, and now a computer model shows that the trick would also be remarkably inefficient.Adding iron to patched of ocean can make plankton bloom temporarily. The microscopic organisms suck up dissolved carbon dioxide from the water, which in turn is replaced by carbon dioxide from the air. ______Jorge Sarmiento from Princeton and his colleagues developed a complex computer model to analyze how factors such as ocean chemistry and water circulation would affect the process if 160,000 square kilometers of ocean were seeded with iron for a month. They found that 100 years later only between 2 and 13 percent of the extra carbon that was originally taken up plankton had actually been removed from the atmosphere.In their scenario, which covers an area 10 times as big as the largest experiment of this kind ever proposed, fertilizing the ocean removes 1 million tons of carbon from the atmosphere just 0.2 percent of the carbon dioxide humankind spews out each month. Rough estimates in the past have predicted similarly disappointing results."These are newer and better models," says Sallie Chisholm, an environmental engineer from the Massachusetts Institute of Technology."Butthe take-home message is the same. Ocean fertilization is not the answer to global warming."【单选题】

A.Its opponents argue, however, that it will stop global warming.

B.Its opponents fear that will damage the marine ecosystem, and now a computer model shows that the trick would also be remarkably inefficient.

C.As plankton die and settle on the ocean floor, their carbon is supposedly locked up in the seabed.

D.They found that 100 years later only between 2 and 12 percent of the extra carbon that was originally taken up plankton had actually been removed from the atmosphere.

E."These are newer and better models,"

F.Ocean fertilization is not the answer to global warming.

正确答案:C

答案解析:空白前句句意：微小生物体在水中吸收溶解的二氧化碳，而水中被吸收的二氧化碳又会被空气中的二氧化碳所替代。

4、Seeing Red Means Danger AheadThe 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 other 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 ______ 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.results

B.rules

C.tools

D.methods

正确答案:A

答案解析:本句意为其实验结果令人振奋，所以应选results。

5、Black HolesMost scientists agree that black holes exist but are nearly impossible to locate. A black hole in the universe is not a solid object, like a planet, but it is shaped like a sphere (球体). Astronomers (天文学家) think that at the center of a black hole there is a single point in space with infinite (无限的) density (稠密).This single point is called a singularity (奇点). If the singularity theory is correct, it means that when a massive star collapses, all the material in it disappears into the singularity. The center of a black hole would not really be a hole at all, but an infinitely dense point. Anything that crosses the black hole is pulled in by its great gravity.Although black holes do exist, they are difficult to observe. These are the reasons,?No light or anything else comes out of black holes. As a result, they are invisible to a telescope.?In astronomical terms, black holes are truly. For example, a black hole formed by the collapse of a giant star would have an event horizon (视界) only 18 miles across.?The nearest black holes would be dozens of light years away from Earth. One light year is about 6 trillion (万亿) miles. Even the most powerful telescopes could not pick out an object so small at such a great distance.In 1994 the Hubble Space Telescope provided evidence that black holes exist. There are still answers to be found, however, so black holes remain one of the mysteries of the universe. (2007年)The nearest black holes are hundreds of light years away from us.【单选题】

A.Right

B.Wrong

C.Not mentioned

正确答案:B

答案解析:题干大意：离我们最近的黑洞也有几百光年。用中心词nearest定位，原文倒数第二段提到：The nearest black holes would be dozens of light years away from Earth. 离地球最近的黑洞有几十光年(dozens)，而不是“hundreds”。故答案选B。