问题补充：
I kept looking at the man, wondering .
A. whether I have seen him before
B. whether I had seen him before
C. that I had seen him before
D. when I saw him before
答案：
A. whether I have seen him before
(答案→)B. whether I had seen him before
C. that I had seen him before
D. when I saw him before
解析：这题考查宾语从句的时态 ，因为是before强调的是过去的过去，要用过去完成时，wonder“想知道”后面应该是疑问词引导的宾语从句。选B。
