【题目】The scientist found a cure for the disease, ____ approximately 600 clinical cases.
A.studyingB.to studyC.having studiedD.to have studied
在线课程【答案】C
【解析】
考查非谓语动词。句意：这个科学家在做了大约600个临床试验后，找到了这个疾病的治疗方案。根据逻辑顺序，应当是先做了临床试验，才能确定治疗方案，所以用having studied作状语。故选C。