如图所示，地面受到的弹力的大小等于 [ ] A．A和B产生的压_爱下问搜题

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问题不定项选择

如图所示，地面受到的弹力的大小等于

[ ]

A．A和B产生的压力之和

B．B对地面的压力

C．A的重力加上B对地面的压力

D．A和B的重力之和

答案

BD

选择题

More than three-fifths of the people caught in the earthquake _____ by the end of last night.

A. were rescued
B. had been rescued
C. had rescued
D. have rescued

多项选择题

信息开发的主要形式有()。

A.剪报

B.索引

C.通知

D.简讯