Use am/is/are going to for something you have already decided to do, and for something the present situation shows is about to happen. Use was/were going to for an intention that did not come off.
A I'm going to do: a decision already made
I am going to do something means I have already decided to do it. I intend to do it.
The decision comes first; the going to simply reports it.
- "Are you going to have a pudding?" "No, I'm stuffed."
- "I hear Tom's been made redundant. What's he going to do?" "He's going to set up his own business."
- I'm just going to nip to the cashpoint. Will you wait here?
- This milk's gone off. I'm not going to drink it.
B I am doing and I am going to do
I am doing means it is already fixed or arranged. You have booked it, or agreed it with somebody.
I am going to do means you have decided to do it. You may have arranged it, or you may not.
Often the difference is small, and either form is possible.
- I'm flying to Belfast on Friday. I've got my boarding pass.
- What time are you seeing the plumber tomorrow?
- "The grass is very long." "I know. I'm going to cut it." (I've decided to, but I haven't arranged it with anybody.)
- This hotel is dreadful. Tomorrow I'm going to find somewhere else.
- I don't know what I'm doing on Saturday. (I don't know my plans.)
- I don't know what I'm going to do about the damp in the bathroom. (I haven't decided.)
C Something is going to happen: you can see it coming
You can also say that something is going to happen when the situation now makes it clear.
A woman is reading her phone as she walks along the pavement. A lamp post is two steps in front of her. She is going to walk into the lamp post. We can see this now, because of what is happening now. The lamp post, for its part, has no plans to move.
- Look at that sky. It's going to pour down. (we can see the clouds now)
- I've eaten far too much. I think I'm going to burst. (I feel full now)
- Prices are already high, and they're going to rise again next year.
D I was going to do: an intention that did not happen
I was going to do something means I intended to do it, but I did not do it.
You can also say that something was going to happen when it looked likely but did not happen.
- We were going to get the bus, but in the end we walked.
- I was just going to ring you when you texted me.
- I thought the match was going to be cancelled, but it went ahead.
Exercises
20.1 Write questions with going to, using the words in brackets.
Your friend has been given a voucher for a hundred pounds. You ask: (what / buy?)
What are you going to buy?
What are you going to buy with it?
Your friend is going to a fancy dress party on Saturday. You ask: (what / go as?)
What are you going to go as?
Your friend has just bought a huge painting. You ask: (where / hang?)
Where are you going to hang it?
Your friend has decided to get married next summer. You ask: (who / invite?)
Who are you going to invite?
Your friend has just bought a bag of mussels for tea. You ask: (how / cook?)
How are you going to cook them?
20.2 Complete the sentences using I'm going to ... or I'm not going to .... Choose from the box.
complainlearnentersayrevisecleannot/acceptnot/drinknot/tell
This milk smells sour. I'm not going to drink it.
This milk smells sour. I'm not going to drink it.
I failed my last exam. This time properly.
I failed my last exam. This time I'm going to revise properly.
I'm best man at my brother's wedding, and I have no idea what .
I'm best man at my brother's wedding, and I have no idea what I'm going to say.
"The oven is filthy." "I know. it at the weekend."
"The oven is filthy." "I know. I'm going to clean it at the weekend."
They've offered me a promotion, but it. It means moving to Aberdeen.
They've offered me a promotion, but I'm not going to accept it. It means moving to Aberdeen.
One day to play the piano properly, though I haven't found a teacher yet.
One day I'm going to learn to play the piano properly, though I haven't found a teacher yet.
the Great North Run next year. I've been training since March.
I'm going to enter the Great North Run next year. I've been training since March.
We've been waiting an hour for our food and it's cold. .
We've been waiting an hour for our food and it's cold. I'm going to complain.
Mum would only worry, so her about the accident.
Mum would only worry, so I'm not going to tell her about the accident.
20.3 What is going to happen in these situations? Use the words in brackets.
The sky over the hills has gone almost black. (pour down)
It's going to pour down.
It's going to pour down.
It is 8.50. Kayleigh's interview starts at 9.00, and she is still twenty minutes away. (late)
She's going to be late.
A small dinghy has a crack in the bottom, and water is pouring in. (sink)
The dinghy is going to sink.
Owen and Sam are driving across the moors at night. The petrol light has been on for twenty miles, and the next garage is thirty miles away. (run out of petrol)
They're going to run out of petrol.
A tree fell on Pete's roof in the storm. Now the roof needs to be repaired. (cost a lot)
It's going to cost a lot to repair the roof.
20.4 Complete the sentences with was/were going to. Choose from the box.
bebuygive upringplaysaytravel
We were going to travel to Scotland by train, but the tickets were so expensive that we drove.
We were going to travel to Scotland by train, but the tickets were so expensive that we drove.
I a birthday card for Gran yesterday, but the shop had closed by the time I got there.
I was going to buy a birthday card for Gran yesterday, but the shop had closed by the time I got there.
Ahmed and I golf on Sunday, but it rained all day.
Ahmed and I were going to play golf on Sunday, but it rained all day.
I the bank about the mistake, but I sorted it out online in the end.
I was going to ring the bank about the mistake, but I sorted it out online in the end.
I thought the driving test really difficult, but I passed first time.
I thought the driving test was going to be really difficult, but I passed first time.
Kerry her course, but her tutor persuaded her to stay.
Kerry was going to give up her course, but her tutor persuaded her to stay.
Sorry, I talked over you. What you ?
Sorry, I talked over you. What were you going to say?