現(xiàn)在完成時
構(gòu)成：主語+助動詞have, has+過去分詞
用法：
1) 表示過去發(fā)生的和現(xiàn)在有某種聯(lián)系的動作，常和just, usually, already, since等時間副詞連用。
I have just had lunch. (飽了，不用再吃了。)
He has had a cup of tea.(不渴了，不用再喝。)
They have already had their holiday. (不能再度假了。)
The boy has already read the book. (已經(jīng)知道書的內(nèi)容了，不用再看了。)
2) 詢問別人是否做過某事一般用現(xiàn)在完成時：
Have you finished your homework?
Have you been to Beijing?
Have he seen the film?
3) 表示開始于過去并持續(xù)到現(xiàn)在的動作
I have lived in Beijing for twenty years.
I have worked for this school for 1 year.
4) 表示一種經(jīng)歷，經(jīng)驗(yàn)：去過…地方，做過…事情，經(jīng)歷過…事情
I have never had a bath.
I have never seen a film.
I have never been to cinema.
I have ever been to Paris.
Have been to表示去過，have gone to 表示去了
I have been to London.(人已經(jīng)回來)
He has gone to London.(人還在那里)
5) 表示一種結(jié)果， 一般不和時間副詞聯(lián)用
I have lost my pen.
I have hurt myself.
He has become a teacher.
She has broken my heart.
句型變化：
★變疑問句將助動詞移到句首，變否定句在助動詞后面加not.
Have you lost your pen? I have not lost my pen.
★肯定回答及否定回答
Yes, I have. / No, I have not.
★特殊疑問句
What have you done?
What has he done?
一般過去時與現(xiàn)在完成時的區(qū)別：
凡是有明確的表示過去的時間狀語的句子為過去時。
注意：有些動詞表示的動作有一個終點(diǎn)，不能再延續(xù)，因此不能和表示一段時間狀語連用。
錯：I’ve left Beijing for 3 days.
對：I left Beijing 3 days ago. I have been away from being for 3 days.