since then意为 "从那时以来"，通常与动词的现在完成时连用，指从过去某一时刻起到现在为止的一段时间。
Since then 前后一般接现在完成时，从那以后，现在完成时表示过去的某件事对现在还有影响， 现在完成时的标志性时间状语already , ever , never , yet , just , before, still , lately ,since , for a long time ,up to now, until,so far,in the last few years/weeks/mouths , till now,recently
Since then, he has developed another bad habit.
从那以后,他养成了另一种坏习惯。
He hasn't come close to those numbers since then.
自那以后，他从没有达到那赛季的表现。
Ah, times are greatly changed since then!'
“啊，从那时起，世道可变得多厉害呀！”
Exactly three years have passed since then.
从那时起，整整3年过去了。
since的用法
for和since的用法区别
since then的用法
ever since的用法
as soon as的用法