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问题 单项选择题

材料在拉力作用下，断裂前横截面上的最大应力称（）。

A.脆性

B.塑性

C.强度极限

D.韧性

答案

参考答案：C

单项选择题

D


An Englishman named Phil Shaw invented extreme ironing in 1997 because he was bored doing ironing at home.
Extreme ironing is a special kind of outdoor sport. It combines (使结合)danger and excitement with practical ironing.
Who does extreme ironing People all over the world who like danger do it. There are about 1000 people around the world who do extreme ironing. There are extreme ironing clubs and groups in Britain, Germany, South Africa, New Zealand and the United States. You don’t have to have any special qualifications(资格证明)to do it. In fact, anyone can do it. However, it is better to start ironing in your back yard(院子) before you start to iron on top of a mountain.
There are, of course, some rules in extreme ironing. The ironing must be outdoors. You must take an iron, an ironing board, and something that you actually iron to get the wrinkles out. Outdoors includes faraway and unusual places, such as on top of a mountain, while skiing, snowboarding, skydiving, or under water. There are no limits. The more unusual the better. However, you should plan carefully because weather conditions can suddenly change on mountains, for example. You should not do extreme ironing on your own.
What kind of things should you have Your must have a real iron. Travel irons are acceptable. You must not use plastic or toy irons. The clothes you iron must he at least the size of a hand towel. It shouldn’t be just a handkerchief. The board doesn’t have to be a full-size board, but that is preferred. It must be one meter long and thirty centimeters wide and have legs. You must also have proof (证据) of ironing that is either a photo or a video, and it should show a recognizable landmark. Be aware (意识) that people have already ironed near the top of Everest, the highest mountain in the world, and in the Blue Hole in Egypt, one of the most dangerous places to dive. However, there are still many records to break. Iron on!

What must you do in extreme ironing ( )

A．Iron outdoors.

B．Iron in good weather.

C．Dive in the Blue Hole.

D．Ski near a mountain.
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多项选择题

NOKIA系统中，为了减少某个基站的话务量，以下参数有那些可以产生作用？（）

A.BLT

B.REO和PET

C.MQL和TLC、TLH

D.RXP
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