Cheatsheet: Modal verbs

Modal verbs

Can and Could

Point	Rule	Example
Form	subject + can + base verb; one form for every subject	She can swim.
Negative	can't; the full form is cannot, one word	I can't swim.
Question	Can + subject + base verb; no do	Can you swim?
Ability	can for skills	I can cook pasta.
Permission	can allows, can't forbids; ask with Can I…?	You can park here. / Can I open the window?
Request	Can you…? asks for help	Can you help me, please?
A2Past ability	could for general ability in the past	I could run fast when I was young.
A2Polite request	Could is more polite than can	Could you open the door, please?
A2Possibility	could says what may happen	It could rain later.
A2Other tenses	be able to takes the place of can	I'll be able to help you tomorrow.
A2Trap	a single success in the past takes was / were able to	The fire was big, but we were able to escape.

Must and Have To

Point	Rule	Example
Form: must	subject + must + V; one form for every subject	She must study.
Form: have to	have to, but has to with he, she, it	We have to leave. / He has to leave.
Question, negative	have to takes do / does / did and then the base form	Do you have to leave? / She doesn't have to leave.
must	the speaker's own view or a written rule	I must save more money. / Visitors must sign in.
have to	the situation or another person decides; common in speech	I have to get up at six for work.
mustn't	forbidden	You mustn't use your phone here.
don't have to	not necessary: you can choose	You don't have to come.
Trap	had to is the past of must	I had to work on Saturday.

Should

Point	Rule	Example
Form	subject + should + base verb; one form for every subject	You should see a doctor.
Negative	shouldn't; no do	You shouldn't work so late.
Question	Should + subject + base verb; no do	Should I take the bus? / What should I do?
Advice	should for a good idea, shouldn't for a bad one	You should drink more water. / You shouldn't eat so much sugar.
Opinion	what you think is right or good	I think the government should build more parks.
Should or must	should: advice or a mild duty; must: a strong obligation or a rule	You should wear a coat. / You must wear a seat belt.
Trap	a negative opinion puts don't on think	I don't think you should go.

May and Might

Point	Rule	Example
Form	subject + might / may + base verb; one form for every subject	She might come.
Negative	might not / may not	He might not come.
Possibility	something possible, now or in the future	She might be at home. / We might go to the beach.
Might or may	might sounds a little less sure	It might rain. / It may rain.
Possibility question	ask with think + will	Do you think it will rain?
B1Permission	May + subject + base verb asks; may allows in formal rules	May I use your phone? / Guests may use the pool until 10.
B1Certainty	will is sure, probably very likely, may / might possible	She will come. / She'll probably come. / She may come.
Trap	may be follows the subject; maybe starts a clause	He may be late. / Maybe he is late.

Would

Point	Rule	Example
Want	would like + noun / to base verb; short form 'd	I'd like a coffee, please. / I'd like to book a table.
Question and offer	Would + subject + V; no do	Would you like some cake?
B1Form	subject + would / 'd + V; negative wouldn't	She would help. / I wouldn't go.
B1Polite request	Would you…? asks politely for help	Would you pass the salt, please?
B1Imagined situation	with if: if + past simple, would + base verb	I would buy a boat. / If I had more time, I would learn Italian.
B1Past habit	repeated actions; the sentence needs a past time frame	When I was a child, we would play outside every day.
B1Trap	used to for a past state: live, be, have, know	When I was young, I used to live in Paris.