22．--- Jack, you look so great！
--- Thanks! I have lost 20 pounds since I ______ my personal trainer six months ago．
A
hired
B
have hired
C
hire
D
had hired
since引导的时间状语从句用过去式，主句用现在完成时。所以选A。
考查动词的时态。
没有分清楚主从句而误选B。