To get a better view of the stage, ____________________.

A．our seats had to be changed.

B．our seats were changed

C．our seats are changed

D．we had to change our seats.

脑梗死后CT出现低密度改变的时间一般是（）

A.发病后即刻

B.发病后1周

C.发病后1月

D.发病后6h

E.发病后1～2天