3）现在完成时可表示持续到现在的动作或状态，动词一般是延续性的，如live, teach, learn, work, study, know.。 
一般过去时常用的非持续性动词有come, go, leave, start, die, finish, become, get married等。例如： 
I saw this film yesterday. （强调看的动作发生过了） 
I have seen this film. （强调对现在的影响，电影的内容已经知道了） 
Why did you get up so early? （强调起床的动作已发生过了） 
Who hasn’t handed in his paper? （强调有卷子未交，疑为不公平竞争） 
He has been in the League for three years. （在团内的状态可延续） 
He has been a League member for three years. （是团员的状态可持续） 
句子中如有过去时的时间副词（如yesterday, last, week, in 1960）时，不能使用现在完成时，要用过去时。 
（错）Tom has written a letter to his parents last night. 
（对）Tom wrote a letter to his parents last night.

8. 用于现在完成时的句型 
1）It is the first / second time.... that…结构中的从句部分，用现在完成时。例如：
It is the first time that I have visited the city. 这是我第一次访问这城市。 
This is the first time （that） I’ve heard him sing.　这是我第一次听他唱歌。 
注意：It was the third time that the boy had been late. 
2）This is +形容词最高级+that…结构，that 从句要用现在完成时。例如： 
This is the best film that I’ve （ever） seen. 这是我看过的最好的电影。