The 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
The 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
B
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。