Question

in a long time amp;for a long time，两者有怎样的不同

Answer 1

in a long time 好久以来，在很长时间内，表示一个范围
I Haven't Seen You in a Long Time
我有好长时间没见到你了
He got off the best line I've heard in a long time.
他说出了我很长时间没有说出的好诗句。

for a long time 很长一段时间，常与现在完成时连用
He would often stare at the black print for a long time.
他常常久久地盯着那些黑色的印刷字体。
He has been waiting for his brother for a long time.
他等候他兄弟已很久了。

比较例句可以体会出差别的。
久久的看/等/......就只能用for a long time