问题
选择题
You will have to wait for one more week, _____ the manager will be back from his trip.
A．after
B．while
C．when
D．since
答案
答案：C
when引导的非限定性定语从句，本句中的when =" by" which time，“到那时候”。after和since都错在时间的先后顺序，而while引导时间状语从句不用将来时。