另外，若有迹象表明要发生某事，用be going to，而不用will。如：

Look at those black clouds. It's going to rain. 看那些乌云。要下雨了。

四、现在完成时的用法

1.表示过去发生的动作对现在所造成的影响或表示从过去某一时刻开始一直延续到现在的动作或状态。如： Have you considered going abroad to study? 你有没有考虑过出国留学？

The storm has lasted for three hours. 暴雨已经持续下了3个小时了。

2.经常与现在完成时连用的状语或结构有already, just, so far, in the last [past] few years, it is the first time that..., for five years, since 1980等。如：

I've known her for a long time. 我认识她很长时间了。

I've already posted your letters. 我已把你的信寄出去了。

So far there has been no bad news. 到现在为止还没有坏消息。

Since then, he has developed another bad habit.自那以后，他养成了另一个坏习惯。

Ⅱ 合作探究：

1. Maya has been a professional since 1989. 2. So far, it has rained for five hours.

3. Joe has been a student here since March. 4. I haven't been to the cinema for ages.

5. Mary has kept a diary since she was ten years old.

观察以上句子，for和 since的区别为：

for 是介词，（词性）而since可作介词或连接词；for 后面跟表示时间段的结构

since后面跟表示时间点的结构。（点∕段）

Ⅲ 课堂检测 (C级) 单项填空（BDACD ACADC ）

1.We ________on our project day and night in the past two weeks.

　A．had worked　B．have worked C．will be working D．are working

2．-Ann is in hospital.

-Oh，really？I ________ know. I________ go and visit her.

　A．didn't；am going to B．don't；would C．don't；will D．didn't；will

3．I used to drink a lot of tea but these days I ________ coffee.

　A．prefer B．preferred C．have preferred D．am preferring

4.Progress____so far very good and we are sure that the work will be finished on time.

A．was B．had been C．has been D．will be

5．-Have you got any job offers? -No.I________.

　A．waited B．had been waiting C．have waited D．am waiting

6.Mr.Blake____Shanghai in a few days.Do you know when the earliest plane____on Sunday? A．is leaving；takes off B．leaves；takes off

C．is leaving；is taking off D．leaves；is taking off

7．-Have you handed in your schoolwork yet?

-Yes，I have. I guess it ________ now.

　A．has graded B．is graded C．is being graded D．is grading

8．I'll come to call on you the moment I ________ my work.

　A．finish B．will finish C．had finished D．will have finished

9．-How can I apply for an online course?

-Just fill out this form and we ________ what we can do for you.

　A．see B．are seeing C．have seen D．will see

10．Because the shop ________，all the T-shirts are sold at half prices.

　A.has closed down B.closed down C.is closing down D.had closed down