现在完成时，过去发生并且已经完成的动作对现在造成影响或后果，过去某一时间开始并一直持续到现在的动作或状态。
基本结构：主语+have/has+动词的过去分词(done)
1.现在完成时用来表示现在之前已发生过或完成的动作或状态,但其结果却和现在有联系,也就是说,动作或状态发生在过去但它的影响现在还存在.
I have spent all of my money.(含义是:现在我没有钱花了.)
Jane has laid the table.(含义是:现在桌子已经摆好了.)
2.现在完成时可以用来表示发生在过去某一时刻的,持续到现在的动作（用行为动词表示）或状态（be动词表示）常与for（+时间段）,since（+时间点或过去时的句子）连用.
①for+时段
②since+过去一个时间点（译为：自从……以来）
③since+时段+ago
④since+从句（过去时）
⑤It is+时段+since+从句（过去时） Mary has been ill for three days. I have lived here since 1998.
注：瞬间动词（buy,die,join,lose……）不能直接与for since 连用。
3.现在完成时不能单独与准确时间连用，(如表示过去的时间状语）
如yesterday(morning、afternoon),last(morning、afternoon)等，除非与for,since连用.
4.现在完成时往往同表示不确定的过去时间状语连用
,如already（肯定）, yet（否定，疑问）, just, before, recently,still, lately等: He has already obtained a scholarship.
5. 现在完成时常常与表示频度的时间状语连用,
如often, sometimes, ever, never, twice, on several occasion等:
6. 现在完成时还往往可以同包括现在时间在内的时间状语连用,
如now, up to these few days/weeks/months/years, this morning/week/month/year, just, today, up to present, so far等:
7. 现在完成时还可以用来表示过去的一个时间到现在这段时间内重复发生的动作. We have had four texts this semester.
8. has gone (to),has been (to), has been (in) 的区别 gone:去了没回been to :去过 been in：呆了很久
练一练：
1.Have you ever _____to the Great Wall? It\'s very beautiful.
A gone B been C went D go
2.Her brother _____the Party since 1978.
A joined B has joined C has been in D was in
3.The Greens _____many places of interest since they came to China.
A will visit B visited C have visited D visit
4.I\'m sorry, I ____ your name.
A had forgotten B forgot C have forgotten D forgotten
5.The bookshop _____ for eight years.
A has been open B has been opened Chas opened D has open
1. B 2. C 3. 4. 8 5. 9 A
