I don’t like any humor in this serious speech because I can’t think of any circumstance ______ this would be beneficial or useful.

A．which

B．whether

C．where

D．as

不属于高分辨力CT扫描技术特点的是（）

A.HRCT具有极好的空间分辨力

B.HRCT与肺功能检查有更好的相关性

C.HRCT扫描层多、层薄、条件大

D.HRCT完全可替代常规CT

E.HRCT扫描不需造影增强