试验研究中对照组与试验组发病率差值再除以对照组发病率,所得指标为
A.有效率
B.治愈率
C.生存率
D.保护率
E.效果指数
参考答案:D
The volcano erupted violently; yet the village at the foot of it should __________. [ ]
A. come through
B. go through
C. get through
D. pass through