------Did you attend Professor Johnson’s lecture about the evolution of videos and sound devices?

------I wish I __________. I __________ a job interview with the UN.

A．had, had

B．had, was having

C．could, have had

D．could have, were having

称重法获得不规则形状物体重心时，常采用吊称物体的（）位置。

A.重心

B.中心

C.一端

D.整体