You can’t imagine what great trouble the doctor had the patient.
A. treats
B. treating
C. to treat
D. treated
网友回答
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。