A doctor can expectat any hour of the day or night.A. callingB. to callC. being calledD.

问题补充：

A doctor can expectat any hour of the day or night.

A. calling

B. to call

C. being called

D. to be called

答案：

A. calling

B. to call

C. being called

(答案→)D. to be called

解析：expect后跟不定式作宾语,call与doctor之间是被动关系。