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问题 单项选择题

所谓有效孔隙，就是孔径在0.0002mm以上的互相连通的，且在（）下流体可在其中流动的孔隙空间。

A.一定压力

B.自然条件

C.一定温度

D.一定压差

答案

参考答案：D

选择题

In ____ accident _____ knowledge of first aid can make _____ real difference.

A．an; a; a

B．the; a; the

C．an; the; 不填

D．a; a; 不填
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选择题

Are the parents who let their child who is ______ walk in the dark alone at night considerate?

A．young enough

B．too young to

C．not old enough to

D．so young
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