- Has your friend completed his design?   - Not yet. He ________ on it last night.

A．worked

B．has worked

C．is working

D．was working

主动脉粥样硬化形成的主动脉瘤最常见于（）。

A.冠状动脉开口处

B.肾动脉开口处

C.主动脉弓

D.降主动脉

E.腹主动脉