在比例极限内线杆件应变与正应力()。 A.为零 B.不变 C.成反比 D.成正比

题型:单项选择题

问题:

在比例极限内线杆件应变与正应力()。

A.为零

B.不变

C.成反比

D.成正比

考点:材料员材料员专业基础知识材料员专业基础知识题库
题型:单项选择题

水果店有苹果64千克,梨是苹果的4倍,把这些梨平均装在8个筐里,每个筐里有多少千克?

题型:单项选择题

12的全部因数有:______、______、______、______、______、______,其中______是奇数,______是偶数;其中______是质数,______是合数.

题型:单项选择题

Aspirin is one of the safest and most effective drugs invented by man. The most popular medicine in the world today, it is an effective pain reliever. Its bad effects are relatively mild. It is also cheap.For millions of people suffering from arthritis, it is the only thing that works. Aspirin, in short, is truly the 20th-century wonder drug. It is also the second largest suicide drug and is the leading cause of poisoning among children. It has side effects that, although relatively mild, are largely unrecognized among users.Although aspirin was first sold by a German company in 1899, it has been around much longer than that. Hippocrates, in ancient Greece, understood the medical value of tree barks and leaves which today are known to contain a chemical found in aspirin. During the 19th century, there was a great deal of experimentation in Europe with this chemical, and it led to the introduction of aspirin. By 1915, aspirin tablets were available in the United States.A small quantity of aspirin relieves pain and inflammation. It also reduces fever by affecting some of the body’’s reactions. Aspirin is very irritating to the stomach lining. The best way is to chew the tablets before swallowing them with water, but few people can stand the bitter taste. Some people suggest crushing the tablets in milk or orange juice.

The second paragraph points out that________.

A.aspirin is always safe

B.aspirin can be dangerous

C.aspirin has been long used

D.aspirin is not truly effective

题型:单项选择题

治疗痛经气血虚弱证应首选

A.归肾丸

B.圣愈汤

C.大补元煎

D.补中益气汤

E.调肝汤

题型:单项选择题

集装式机械密封的特点是什么?

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