— How did you like Nick's performance last night?

— To be honest, his singing didn't _____ to me much. [ ]

A. appeal

B. belong

C. refer

D. occur

制造和维持一个是内镜手术操作的关键（）。

A、方便操作的视腔

B、隐蔽的切口

C、生理轮廓线

D、流畅的外形

E、以上均不是