问题补充:
.He was about to leave the telephone rang; was from his mother.
A. when; that
B. before; which
C. when; it
D. before; this
答案:
A. when; that
B. before; which
(答案→)C. when; it
D. before; this
解析:句意:他即将离开这是电话响了,是母亲打来的。句型: be about to do …when,即将做某事,正在那时,第二空用it ,指代前面的电话,所以选C。