肛瘘行挂线疗法的最大优点是（）
A.不会造成肛门失禁
B.不会发生急性感染
C.操作简单
D.出血少
E.皮肤切口不会粘合
参考答案：A
Shirley _____ a book about China last year but I don't know whether she has finished it. [ ]
A. has written
B. wrote
C. had written
D. was writing
