检验检疫机构对进口石材实施登记备案、专项检测制度。
参考答案：错
David is so curious that no one can ________ from finding out what is going on.
A．hold him back
B．hold him up
C．hold to him
D．hold him down
机械设备的重大事故是指机械直接损失价值在（）元以上者。
A.5000
B.10000
C.15000
D.20000
