he field research will take Joan and Paul about five months; it will be a long time we me

问题补充：

he field research will take Joan and Paul about five months; it will be a long time we meet them again.

A. after

B. before

C. since

D. when

答案：

A. after

(答案→)B. before

C. since

D. when

解析：该空表示在我们再见面之前要过很长时间，因此应填before引导时间状语从句。