完成时态1。
用法：①过去发生的动作对现在造成的影响或结果：强调结果E。
g：Yesterday I finished my homework, that's to say, I have finished my homeworknow。
②过去已经开始一直持续到现在的动作或状态：强调继续E。
g.::I have lived here since 1990。
2. 现在完成时的构成have\has+过去分词3. 现在完成时的四个基本句型肯定句He has finished the work.一般疑问句Has he finished the work?否定句He has not finished the work.两回答Yes ，he has。
No，he hasn’t.特殊疑问句What has he done?4。
在下列情形下用现在完成时（1）九词语①already已经肯定句中或句尾e.g.:I have already found my pen.= I have found my pen already.②yet已经否定句和疑问句句尾e.g。
：I have not finished the work yet.Have you bought a computer yet?③ever曾经句中e.g.：Have you ever seen pandas？④never从不句中e。
g.:I have never been to Beijing.⑤just刚刚句中e。
g.：I have just done my work.⑥before以前句尾e.g。
：I have never been there before。
⑦so far到目前为止e。
g.：So far he has learnt 200 words。
⑧how long多久e。
g.：How long have you lived here？⑨how many times多少次e.g.：How many times has he been to Beijing？(2)两词组have〈has>gone to去了某地e。
现在完成时的用法have(has)+过去分词1.现在完成时用来表示现在之前已发生活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 lost my wallet.(含义是:现在我没有钱花了.)Jane has laid the table.(含义是:已可以吃饭了.)Michael has been ill.(含义是:现在仍然很虚弱)He has returned from abroad. (含义是:现在已在此地)2. 现在完成时可以用来表示发生在过去某一时刻的,持续到现在的情况,常与for,since连用. Mary has been ill for three days.I have lived here since 1998.3. 现在完成时往往同表示不确定的过去时间状语连用,如already, yet, just, before, recently, lately等:He has already obtained a scholarship.I haven't seen much of him recently (lately).We have seen that film before.Have they found the missing child yet4. 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:Have you ever been to BeijingI have never heard Bunny say anything against her.I have used this pen only three times. It is still good.George has met that gentleman on several occasions.5. 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, now, just, today, up to present, so far等:Peter has written six papers so far.Man has now learned to release energy from the nucleus of the atom.There has bee too much rain in San Francisco this year.The friendly relations and cooperation between our two countries have been enhanced in the past few years.Up to the present everything has been successful.6. 现在完成时表示现在之前业已完成的动作,虽然其效果或影响仍然存在但已不再继续,但是有一些现在完成时的句子,在后面加上for+一段时间,则现在完成时的动作就表示延续性. Thomas has studied Russian. (现在不再学俄语)Thomas has studied Russian for three years. (=Thomas began to study Russian three years ago, and is still studying it now.(同第2点用法第一个例句)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.===================现在完成时的“完成用法”和“未完成用法”1.现在完成时的"完成用法"现在完成时的"完成用法"指的是动作发生在过去某一时刻并已结束，但该动作对现在产生了影响，与现在情况具有因果关系。
Cici现在完成时名词记忆口诀现在完成时讲解如何使用现在完成时同学们我们已经学习了现在进行时、一般现在时、一般过去时、一般将来时这4种时态的用法，但这4种时态还不能满足我们表达的需要。
比如：表示“某人过去曾经做过某事”或者“某人做某事多久”，以上五种时态就派不上用场了。
这时，我们可以用一种新的时态——现在完成时表示。
一、现在完成时的构成（一）肯定式主语＋助动词have ／has ＋过去分词＋其它说明：这里的have ／has是助动词，没有什么具体意义。
当主语是第三人称单数时助动词用has，其余人称一律用have。
has，have 的缩略式分别为's或've。
规则动词过去分词的构成与过去式的构成方式一样，不规则动词可参看不规则动词表。
实例：1）I've just copied all the new words ．我刚抄写了所有的生词。
(表示不要再抄了)2）She has lost her books ．她丢失了她的书。
（表示到目前为止还没有找到）(如果用过去时：She lost her books . 则强调书是过去丢的这一动作，而不知现在有没有找到)3）We've just cleaned the classroom ．我们刚好打扫了教室。
（表明现在教室是干净的）（二）否定式主语＋助动词have ／has＋not＋过去分词＋其它说明：现在完成时构成否定句时，只需在助动词have ／has后面加not就行。
have not，has not的缩略式分别为haven't ，hasn't。
另外，肯定句中有some，already时，改为否定时要分别改成any，yet。
实例：1）I haven't finished my homework yet．我还没有完成我的作业。
2）She hasn't travelled on a train ．她没有坐火车旅行过。
