问题补充:
he will leave for Beijng.
A. It will not be long before
B. It is before long that
C. It is before long
D. It was before long that
答案:
A. It will not be long before
(答案→)B. It is before long that
C. It is before long
D. It was before long that
解析:这是一个强调句。强调部分是before long。