It is difficult for us to learn a lesson
题型:选择题
问题:
It is difficult for us to learn a lesson in life _____ we've actually had that lesson.[ ]
A. when
B. after
C. since
D. until
It is difficult for us to learn a lesson in life _____ we've actually had that lesson.[ ]
A. when
B. after
C. since
D. until