机铰时，应使工件（）装夹进行钻、铰工作，以保证铰刀中心线与钻孔中心线一致。

A、一次

B、二次

C、三次

D、四次

Teaching and learning are parts of the same educational experience, but unfortunately they are often thought of ___________ separate.

A．as if

B．being

C．as

D．like