1. 表示"过去发生的动作或事情对现在"的影响或产生的结果。常与不确定的时间状语连用，如yet, recently, lately.
（1）In the past few years, great changes have taken place in my hometown.
（2）We have had too much rain this year.
2. 表示“从过去某个时间点开始延续到现在”，并可能延续下去的动作。常同表示一段时间的状语连用。如so far, up to now, since, for a long time, till now，in the past\ last few years.
He has worked here for over twenty years.
3. It\ This is the first time that …和This is the best (worst, most interesting )+n. + that…结构的从句要求用现在完成时。
(1)This is the first time thatI have heard her sing.
(2)It’s the best film thatI have ever seen.
4. 句中有since构成的时间状语或引导的时间状语从句，主句用现在完成时态。
Where have you been since I last saw you?
5. 在时间，条件，让步状语从句中，表示将来某时以前已完成的动作。
(1)I will not believe you unless I have seen it with my own eyes.
(2)I will go with you as soon as I have finished my work.
