You can never imagine what great trouble I have had ________ the patient who received a serious wound.
A.treat
B.to treat
C.treating
D.treated
网友回答
C解析做好这题，关键是知道句型 have trouble (difficult) doing sth.做某事有困难．定语从句部分是I have had (great trouble)treating the patient，而 patient后又有一个定语从句．