现在完成时

1. 现在完成时的形式
have/has + 过去分词

2. 现在完成时的用法
1） 表示一件事已经发生，这件事对现在有影响或与现在情况有联系。

* We've finished the work. 我们已经完成了工作。
* Someone has broken the window. 有人把窗户打破了。
* Have you seen my bag? 你看到我的手提包了吗?　 No. I haven't. 不，我没看见。
* I haven't finished my homework. Can you help me？我还没完成我的功课。你可以帮帮我吗？
* My father has read the novel twice. 我爸爸已经看过两遍这本小说了。
* They've bought some plates. You don't have to buy any more. 他们已经买了一些碟子。你不用再买了。
* Who has opened the window? 谁把窗子打开了？

2） 表示持续到现在的状态
* Have you waited long? 你等了很久吗？
* The temperature has stayed hot this week. 这星期天气一直很热。
* We have been busy this afternoon. 今天下午我们一直很忙。
* He has lived here since 1978．自从1978年以来，他一直住在这儿。
* She has stayed in her room for hours！ 她在房间里呆了几个小时了！

3. 现在完成时在表达时常和一些词连用:
1） 常和 just, already, yet , recently, lately, ever, never 等副词连用
* I haven't seen the movie yet. 我还没看这部电影。
* Have you ever sung this English song？你曾唱过这首英文歌吗？
* I've just lost my chemistry book. 我刚才丢了我的化学书。
* We've already returned the car. 我们已经把车还了。
* Recently the problem has aroused people's concern. 最近这个问题引起了人们的关注。
* There have been a lot of changes in our city recently. 我们的城市最近发生了很大的变化。
* Have you heard from your family lately? 你最近收到家人的来信了吗？
* We have never heard of it before．我们从来没有听说过这件事。

2） 常和for, since 等引导的状语连用，或与how long 连用。

* We've learnt English for three years. 我们学习英语已经三年了。
* I haven't met him for a long time. 我好长时间没见到他了。
* How long have they been in China? 他们在中国呆了多长时间了？
* Mr. Smith has worked here since 1984. 1984年以来，史密斯先生一直在这工作。