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问题 单项选择题

钻具的应力腐蚀断裂是金属在（）的共同作用下引起的一种破坏形式。

A、受力严重和冲击载荷

B、拉应力和腐蚀介质

C、弯曲应力

D、外加拉力和残余应力

答案

参考答案：B

选择题

After the new equipment was introduced, they produced ______machines this year as the year before.

A．as twice many

B．as many twice

C．twice as many

D．twice many as

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单项选择题

采用修正量方法对间接测强方法进行钻芯修正时，标准芯样试件数量不应少于（）个。

A.15

B.9

C.6

D.3
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