Several passages were found _________ when the book _________ me.

A．missing; returned

B．lost; was returned

C．gone; was returned to

D．disappeared; was returned to

进行钢筋焊接接头剪切试验时，加载时应连续而平稳，加载速率宜为( )，直到试件破坏为止。

A．10～20MPa/s

B．10～30MPa/s

C．15～20MPa/s

D．15～30MPa/s