无菌器械台的铺巾至少为_________层，四周垂于床缘下_________。
参考答案：4；30cm
Frank’s marriage to the billionaire’s daughter got him through his hardest time, ________years later he wondered what he could have done differently.
A．therefore
B．and
C．however
D．but
电话通知汇款一周内至少通知（）次。
A、1
B、3
C、5
D、7
