问题补充：
Only when be possible to sign the papers.
A. does the boss come will it
B. the boss comes will it
C. has the boss come it will
D. the boss comes it will
答案：
A. does the boss come will it
(答案→)B. the boss comes will it
C. has the boss come it will
D. the boss comes it will
解析：Only加when引导的时间状语从句位于句首构成部分倒装，根据规则主句倒装，从句不变，因此选B.
