下列四种说法中哪个是疲劳破坏的主要特征?()A.疲劳破坏要经历三个阶段所以破坏前有明

题型:单项选择题

问题:

下列四种说法中哪个是疲劳破坏的主要特征?()

A.疲劳破坏要经历三个阶段所以破坏前有明显的塑性变形。

B.金属结构承受的交变应力接近材料的强度极限时才可能导致结构的疲劳破坏。

C.塑性好的金属材料疲劳破坏前有明显的塑性变形;脆性材料则不会有明显的塑性变形。

D.疲劳破坏是一个损伤累积的过程,从疲劳断口可以看到:疲劳源、裂纹稳定扩展区、快速断裂区。

考点:民用航空器维修执照考试M6维护技术基础M6维护技术基础题库
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阅读下面的材料,然后根据材料内容回答问题。

Family members of Chinese people on the Malaysia Airlines Flight MH370 had a candlelight prayer ceremony(祈祷仪式) at the Beijing Lido Hotel on Tuesday for all those on the plane.

They lit 239 candles, each standing for one person. The ceremony started at 0:41 a.m., it was the time the plane began its flying from Kuala Lumpur to Beijing before disappearing(消失) on March 8. When the ceremony ended at 8:11 am, the last time the plane sent signals to a satellite(卫星), a lady cried and fell down on the floor because her husband was on the plane. Then, other people had to take her away from the prayer room to the hospital.

In the past month, the family members felt both hopeful and hopeless. People are not sure where the plane is, because no debris(残骸) from the plane has been found. They said they needed more information about the search from Malaysia Airlines and the Malaysian government.

小题1:Where did people have the ceremony?

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小题2:What time did the ceremony start?

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小题3:Why did that lady cry and fall down?

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小题4:How did those people feel in the past month?

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小题5:What did they need from Malaysia Airlines and the Malaysian government?

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题型:单项选择题

我国年龄在18岁以上的健康公民都有无偿献血的责任和义务。[ ]

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下列哪项不是暑厥的临床表现()

A.猝然昏倒

B.身热肢厥

C.气粗如喘

D.口眼歪斜

题型:单项选择题

蛛网膜下腔出血的常见并发症不包括()。

A.再出血

B.脑血管痉挛

C.急性脑积水

D.迟发性脑积水

E.颅内感染

题型:单项选择题

骨巨细胞瘤的好发年龄是()。

A.1~5岁

B.6~10岁

C.11~15岁

D.16~20岁

E.21~30岁

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