扳道岔时，（）车辆通过。
A.可以
B.随时
C.严禁
D.必要时
参考答案：C
The school ______ in the earthquake is being built by workers from Weifang. [ ]
A. destroyed
B. destroying
C. to destroy
D. destroys
左冠状动脉起自于（）。
A.冠状窦左端
B.主动脉右窦
C.主动脉左窦
D.主动脉后窦
E.冠状窦右端
