定句：主语+have/has+过去分词
否定句：主语+have/has not +过去分词
疑问句：Have/Has+主语+过去分词
7. 现在完成时
(1) 现在完成时的句型结构
①肯定句：主语+ have/has+ 过去分词
②否定句：主语+ have/has+ not+过去分词
③疑问句：Have/Has +主语+过去分词
(2) 现在完成时的用法
①表示到目前为止曾经有过的或未曾有过的经历和体验。常和never, ever, several times等连用。
如：
I’ve never been to Africa.
Have you ever been to Tokyo?
I’ve been there three times.
②. 表示某动作从过去开始，现在刚刚完成，对现在有一定的影响。常与just, already, yet, so far等词语连用。
如：
He has just finished his new book.
注意：just now用于过去时。
③.表示某动作从过去开始，一直持续到现在，可能还会持续下去。通常与for或since连用。如：I have lived in Qingdao for 6
years. /since 6 years ago/since 2003/
since I came to this city.
It is/has been …+ since….
It’s been seven years since we last saw each other.
It’s six years since he was a teacher.
注意:for+一段时间，since后接一个过去的时间点或一般过去时的句子。④在表将来的时间状语和条件状语从句中代替将来完成时。
如：
You can go home when you have
finished your work.
比较：You can go home when you
finish your work.
(3) 过去分词的构成
①一般情况下在动词词尾后直接加-ed。
如：
listen-listened, talk-talked
②以不发音的字母e结尾的动词，直接加-d。
1/2
如：
live-lived, hope-hoped
③以辅音字母加y接尾的动词，y变i，再加-ed.
如：
worry-worried, hurry-hurried
④以重读闭音节结尾，且结尾只有一个辅音字母的动词，双写辅音字母，再加-ed。如：
drop-dropped, plan-planned, stop-stopped
⑤不规则变化
如：
cut-cut-cut, come-came-come
begin-began-begun, lend-lent-lent
