问题补充:
--- Let’s go to play football, shall we?
--- Sorry, I can’t. I must go over the points the teacher explained I forget them.
A. after
B. when
C. before
D. since
答案:
A. after
B. when
(答案→)C. before
D. since
解析:连词辨析。A.在……之后;B. 当……时 C. 在……之前D. 自从……以来。句意:让我们去踢足球,好吗?——抱歉,我不能。我必须在我忘记他们之前复习老师解释过的要点。故选C。