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.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、The book took ten years of thorough research.【单选题】

A.basic

B.careful

C.social

D.major

正确答案:B

答案解析:这本书花了十年时间的精心研究。本题难度不大，干扰项干扰不大，是送分题，thorough的引申意义指“认真的，精心的”，careful是“认真的”意思，所以最佳答案是B。

3、Breastfeeding Can Cut Cardiovascular RiskBreastfeeding can reduce the risk of a heart attack or stroke later in life and could prevent hundreds of thousands of deaths each year, researchers said on Friday. Babies who are breastfed have fewer childhood infections and allergies and are less prone to obesity. British scientists have now shown that breastfeeding and slow growth in the first weeks and months of life has a protective effect against cardiovascular disease. "Diets that promote more rapid growth put babies at risk many years later in ______ of raising their blood pressure, raising their cholesterol and increasing their tendency to diabetes and obesity-the four main risk factors for stroke and heart attack." said Professor Alan Lucas of the Institute of Child Health in London. "Our evidence suggests that the reason why breast-fed babies do better is because they grow more slowly in the early weeks."Lucas said the effects of breastfeeding on blood pressure and cholesterol later in life are greater than anything adults can do to control the risk factors for cardiovascular disease, other than taking drugs. An estimated 17 million people die of cardiovascular disease, particularly heart attack and strokes, each year, according to the World Health Organization. Lucas and his colleagues compared the health of 216 teenagers who as babies had either been breastfed or given different nutritional baby formulas\' They reported their findings in The Lancet medical journal. The teenagers who had been breastfed had a 14 percent lower ratio of bad to good cholesterol and lower concentrations of a protein that is a marker for cardiovascular disease risk. The researchers also found that regardless of the child\'s weight at birth, the faster the infants grew in the early weeks and months of life, the greater was their later risk of heart disease and stroke. The effect was the same for both boys and girls. "The more human milk you have in the newborn period, the lower your cholesterol level is, the lower your blood pressure is 16 years later, "Lucas said. 【单选题】

A.forms

B.cases

C.terms

D.places

正确答案:C

答案解析:与介词in和of构成的固定搭配是：in case of（adv. 假设、万一），in terms of（考虑到）。

4、Better Control of TB Seen if a Faster Cure is FoundThe World Health Organization estimates that about one-third of all people are infected with bacteria that cause tuberculosis. Most times, the infection remains inactive. But each year about eight million people develop active cases of TB, usually in their lungs. Two million people die of it. The disease has increased with the spread of AIDS and drug-resistant forms of tuberculosis. Current treatments take at least six months. Patients have to take a combination of several antibiotic drugs daily. But many people stop as soon as they feel better. Doing that can lead to an infection that resists treatment. Public health experts agree that a faster-acting cure for tuberculosis would be more effective. Now a study estimates just how effective it might be. A professor of international health at Harvard University led the study. Joshua Salomon says a shorter treatment program would likely mean not just more patients cured. It would also mean fewer infectious patients who can pass on their infection to others. The researchers developed a mathematical model to examine the effects of a two-month treatment plan. They tested the model with current TB conditions in Southeast Asia. The scientists found that a two-month treatment could prevent about twenty percent of new cases. And it might prevent about twenty-five percent of TB deaths. The model shows that these reductions would take place between two thousand twelve and two thousand thirty. That is, if a faster cure is developed and in wide use by two thousand twelve. The World Health Organization ______the DOTS program in nineteen ninety. DOTS is Directly Observed Treatment, Short-course. Health workers watch tuberculosis patients take their daily pills to make sure they continue treatment. Earlier this year, an international partnership of organizations announced a plan to expand the DOTS program. The ten-year plan also aims to finance research into new TB drugs. The four most common drugs used now are more than forty years old. The Global Alliance for TB Drug Development says its long-term goal is a treatment that could work in as few as ten doses.【单选题】

A.developed

B.invented

C.delayed

D.refused

正确答案:A

答案解析:空白处的上一句实际上也起到了提示作用，可以推测，本句应该是“制订DOTS计划”，而4个选项中只有A有“制订”的意思，计划也不可能是“发明”，从上下文分析，更不可能是“推迟”或“拒绝”。

5、Waving With LightIn the Sierra Madre mountain range of west central Mexico, the native Huichol people live much the way their ancestors did without electricity. That\'s because it\'s too expensive to string power lines to the remote mountain areas where they live. To help support themselves, the Huichol create beautiful artwork. They sell their art in cities hundreds of miles away from their villages. And without electricity at home or on the road, they can only work during daylight hours. When it gets dark, they must stop whatever they\'re doing. Now, a team of scientists, designers, and architects are using new technologies to provide the Huichol with light after the sun sets. The scientists\' technique involves weaving tiny electronic crystals into fabrics that can be made into clothes, bags, or other items. By collecting the sun\'s energy during the day, these lightweight fabrics provide bright white light at night. Their inventors have named the fabrics "Portable Lights." Portable Lights have the potential to transform the lives of people without electricity around the world, says project leader Sheila Kennedy. "Our invention," Kennedy says, "came from seeing how we could transform technology we saw every day in the United States and move it into new markets for people who didn\'t have a lot of money."At the core of Portable Light technology are devices called high-brightness light-emitting diodes, or HB LEDs. These tiny lights appear in digital clocks, televisions, and streetlights. LEDs are completely different from the light bulbs. Most of those glass bulbs belong to a type called incandescent lights. Inside, electricity heats a metal coil to about 2,200 degrees Celsius. At that temperature, bulbs give of flight we can see. Ninety percent of energy produced by incandescent lights, however, is heat and invisible. With all that wasted energy, bulbs burn out quickly. They are also easily broken. LEDs, on the other hand, are like tiny pieces of rock made up of molecules that are arranged in a crystal structure. When an electric current passes through an LED, the crystal structure produces light. Unlike incandescent bulbs, they can produce light of various colors. Within an LED, the type of molecules and their particular arrangement determines what color is produced. LEDs are different from light bulbs in that____. 【单选题】

A.LEDs are incandescent lights while light bulbs are not.

B.LEDs have a metal coil while light bulbs have not.

C.LEDs emit colored light while most light bulbs don\'t.

D.LEDs are made up of tiny pieces of rock while light bulbs are not.

正确答案:C

答案解析:短文第6段对light bulbs进行了描述。第2句中的those glass bulbs即指第1句中的light bulbs。因此，LEDs不是incandescent lights（白炽灯），也没有金属丝。所以A和B均是错误的。最后一段第一句“LEDs，on the other hand，are like tiny pieces of rock made up of molecules that are arranged in a crystal structure”中的“like tiny pieces of rock”不等于pieces。