问题
选择题
— You look unhappy, my son?
— I'm wondering how long it'll be ________ we come to China again. [ ]
A. since
B. when
C. before
D. after
答案
答案：C
搜题请搜索小程序“爱下问搜题”
— You look unhappy, my son?
— I'm wondering how long it'll be ________ we come to China again. [ ]
A. since
B. when
C. before
D. after
答案：C