20 be going to表达将来

be going to do sth表示打算或决定要去做某事:
A:There's a film on the television tonight. Are you going to watch it?
B:No, i'm tired. I'm going to have an early night. A:I heard Ruth has won some money. What is she going to do with it?
B:She is going to buy a new car.
A:Have you made the coffee yet?
B:I'm just going to make it.
-This food looks horrible. I'm not going to eat it.

上一期节目我们讲了现在进行时可以用来表达将来。那么I'm doing和I'm going to do有什么区别呢？
现在进行时(be doing)通常用来表达已经安排好了，要去做某件事情，比如说见某个人或者是去某个地方：
- What time are you meeting Ann this evening?
-I'm leaving tomorrow. I've got my plane ticket.
Be going to通常用来表达决定去做，但可能并不是安排好的：
A:The windows are dirty.
B:Yes, I know. I'm going to clean them later. A:I've decided not to stay here any longer. Tomorrow I'm going to book for somewhere else to stay.
通常情况下这两种用法都可以，因为它们的区别很小，可以忽略。
——
你也可以用something is going to happen来表达我们确信将来会发生的事。来看一个场景：
一个快递员扛着一个大箱子在路上走。这个大箱子完全遮住了他的视线，而他前进方向不到两米的地方刚好有一个大坑。这个时候我们说：
He is going to fall into the hole.
我们用something is going to happen来表达我们确信这个情形会发生。就像刚才这个例子，我们看到了他前面有一个坑，而且他看不到，所以我们确信它会掉到坑里。
再比如说：
Look at those black clouds. It's going to rain.看那些黑云！快下雨了。在这里我们确信要下雨了，根据是那个黑云现在就在那里。
I feel terrible. I think I'm going to be sick.我觉得很难受，我想我要生病了。在这里我确定自己要生病了，根据是我感觉非常难受。

最后，我们来给大家讲一讲I was going to…这里我们把be动词换成了过去式，表示过去打算要做，但是并没有做的事情，比如：
- We were going to travel by train, but then we decided to go by car instead.
A: Did peter do the examination?
B:No, he was going to do it but he changed his mind.
- I was just going to cross the road when somebody shouted,“stop!”

同样的我们也可以用something was going to happen来表达原来确信要发生的事情，后来没发生:
-I thought it was going to rain. But then the sun came out.