You can’t imagine what great trouble the doctor had the patient.A. treatsB. treatingC. to

问题补充：

You can’t imagine what great trouble the doctor had the patient.

A. treats

B. treating

C. to treat

D. treated

答案：

A. treats

(答案→)B. treating

C. to treat

D. treated

解析：考查固定搭配。the doctor had the patient是定语从句，先行词是great trouble，代入定从，应是the doctor had great trouble（in）treating the patient，考查做某事有困难结构，所以选B。