— Has your father returned from Africa yet? 

— Yes, but he _____ here for only three days before his company sent him to Australia. [ ]

A. was

B. has been

C. will be

D. would be

下列关于钢管扣件脚手架优点说法不正确的是（）。

A.通用性强

B.装拆灵活

C.搬运方便

D.承载能力强