问题补充:
The teacher explained a second time, the students should have difficulty in doing the experiment.
A. although
B. in case
C. so that
D. but
答案:
A. although
(答案→)B. in case
C. so that
D. but
解析:句意:老师又解释了一次,以防学生们在做实验时有困难。Although尽管;in case万一;so that以便;but但是。根据句意故选B。