请问before long与since then的区别

请问before long与since then的区别 long before和long since 区别 before long 与 long before的区别 请问before long and long before 的区别是什么 long before 与 before long的区别是什么 before long与long before 各用再什么时态! long before 与before long 的区别 ,有什么异同 “long before 与 before long”有什么区别? It's years since l enjoy myself so much.since可否换成before?就像it's not long before before very long与put him right logn before与before long用法有什么区别 befor long 与 long before 的区别用法的不同 not long after与 before long 的区别 John thinks it wont be long _before_ he is ready for his new job.a.when B.after C.before D.since为什么不填after?long before 很久以前） 与before long （不久以后）用法上有何区别?句式上有何异同?最好举例eg!Thanks! long before和before long before 和before long before和before He said that he was going to visit China before long and he had the idea long before.这里long before 与before long