2019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、A lot of people could fall ill after drinking contaminated water.【单选题】

A.muddled

B.polluted

C.mixed

D.troubled

正确答案:B

答案解析:题干大意：很多人喝过受污染的水生病了。画线词contaminated是动词contaminate的过去分词，这里作形容词用，contaminated：受到污染的，故和polluted同义。muddled water和troubled water：混浊的水。mixed water：混合水。故答案选B。

2、Inventor of LED
When Nick Holonyak set out to create a new kind of visible lighting using semiconductor alloys, his colleagues thought he was unrealistic. Today, his discovery of light-emitting diodes, or LEDs, are used in everything from DVDs to alarm clocks to airports. Dozens of his students have continued his work, developing lighting used in traffic lights and other everyday technology.
On April 23,2004, Holonyak received the $500,000 Lemelson-MIT Prize at a ceremony in Washington. This marks the lOth year that the Lemelson-MIT Program at the Massachusetts Institute of Technology (MIT) has given the award to prominent inventors. "Anytime you get an award big or little. It＇s always a surprise. " Holonyrak said. Holonyak, 75, was a student of john Bardeen, an inventor of the transistor, in the early 1950s. After graduate school, Holonyak worked at Ben Labs. He later went to General Electric, where he invented a switch now widely used in house dimmer switches.
Later, Holonyak started looking into how semiconductors could be used to generate light. But while his colleagues were looking at how to generate invisible light, he wanted to generate visible light. The LEDS he invented in 1962 now last about 10 times longer than incandescent bulbs, and are more environmentally friendly and effective.
Holonyak, now a professor of electrical and computer engineering and physics at the University of Illinois, said he suspected that LEDs would become as commonplace as they are today, but didn＇t realize how many uses they would have.
"You don＇t know in the beginning. You think you＇re doing something important. You think it＇s worth doing, but you really can＇t tell what the big payoff is going to be, and when, and how. You just don＇t know, "he said.
The Lemelson. MIT Program also recognized Edith Flanigen, 75, with the $100,000 Lemelson-MIT Lifetime Achievement Award for her work on a new generation of "molecular sieves", that can separate molecules by size.
Holonyak was the inventor of the transistor in the early 1950s.
【单选题】

A.Right

B.Wrong

C.Not mentioned

正确答案:B

答案解析:答案相关句：Holonyak, 75，was a student of John Bardeen，an inventor ofthe transistor，in the early 1950s（该句所反映的内容是：John Bardeen是20世纪50年代初期晶体管的发明者），问题句的内容与原文的内容不一致，因此选B。

3、Breastfeeding Can Cut Cardiovascular Risk
Breastfeeding 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 terms 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 ______ 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.which

B.that

C.something

D.anything

正确答案:D

答案解析:根据语法结构和句意判断D（任何事情）合适。

4、Radiocarbon Dating
Nowadays 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。

5、She can be relied on in a crisis.【单选题】

A.looked after

B.believed in

C.turned on

D.depended on

正确答案:D

答案解析:在危机时她还是可靠的。本题有一定难度，B的干扰性最大，但在确定词的精确意义后，可以发现，relied on和depended on都是“可以依靠的”意思，所以D是最佳答案。