Little ______  that we were watching his every move，so he seemed to be going his own way      in this business.

A．did he know

B．he didn't know

C．didn't he know

D．he knew

薄层扫描需具备的条件是（）。

A.梯度磁场场强高

B.梯度磁场场强低

C.射频带宽要宽

D.射频编码大的步码数

E.相位编码大的步码数