Use should and shouldn’t to ask for and give advice and suggestions:
“I’ve had a really bad headache for the past week.”
“That’s not good – you should go to the doctor.”
“I want to make more friends, but I don’t know how.”
“First of all, you shouldn’t spend so much time on the computer. You should
go out and join a club or start playing a sport instead!”
“I had a fight with my best friend. What should I do?”
“Hmm… I think you should call her and tell her you’re sorry.”
Use could and couldn’t for ability in the past (they are the past forms of can and
can’t):
▶️ When I was younger, I could run a mile in 7 minutes. Now it takes me 20
minutes!
▶️ Yesterday, I couldn’t find my wallet anywhere – but this morning I found it.
▶️ Last year, he couldn’t speak English very well, but now he can.
Use could to talk about future possibilities:
“Do you have any ideas for our publicity campaign?”
“Yes, I’ve got a few ideas. I could put advertisements on Facebook and Google.
We could also give out pamphlets in our neighborhood. Maybe John could
even contact local TV stations.”
Use could to make polite requests:
▶️ Could you please open the window? It’s hot in here.
▶️ Could you turn the music down? Thanks.
▶️ Could you make 10 copies of this report, please?
Use would to talk about unreal or unlikely situations:
▶️ If I were the president of my company, I would make a lot of changes.
▶️ If people were more generous, there wouldn’t be so much poverty in the
world.
▶️ She would travel around the world if she had more vacation time.
In this case, would is often shortened to ‘d
▶️ If I were the president of my company, I’d make a lot of changes.
Use Would you like…? to make polite offers:
“Would you like anything to drink?”
“A soda would be great. Thanks!”
“Would you like to join us for dinner?”
“I’d love to, but I actually have other plans tonight.”
“Would you like to see some pictures from my vacation?”
“Sure!”
Don’t use “to” after should, could, or would:
You shouldn’t to smoke.
You shouldn’t smoke.
We could to order pizza tonight.
We could order pizza tonight.
I would to buy a new car if I had the money.
I would buy a new car if I had the money.