有一栋建筑物高度为101m的酒店，其地上二层有一个宴会厅，长47m，宽20m，顶棚狰高10m，则需装设火灾探测器为（）。

A.10～12个

B.13～14个

C.15～17个

D.20～23个

We were listening closely to the lecture yesterday evening when suddenly the light ________.

A．had been gone out

B．go out

C．was gone out

D．went out