Taking this kind of medicine, if ________, will possibly do him great harm．
A.to continueB.continuedC.continuesD.continuing在线课程B
continue此处用作及物动词，接在if后面，因为与逻辑主语是被动关系，所以要用过去分词，if continued相当于if it is continued，因为从句的主语it代替的就是主句中的主语Taking this kind of medicine，而且从句中有系动词，这种情况下，可把it is省去，构成省略形式。