Grammar
Modal verbs: can, could, should, must, and might
A short change can alter the whole message: You can leave says it is possible; You must leave says it is necessary.
Use common modal verbs to express ability, permission, advice, obligation, and possibility.
Read and practice
Read the examples and try the written questions in this guide. Listening recordings are not available for this lesson yet.
Try the written questions
You should check the address. /juː ʃʊd tʃek ði əˈdres/
The short answer
Use can for present ability or permission, could for past ability or a polite request, should for advice, must for a strong rule or necessary action, and might for a possibility. Put the modal before the base verb: You should check the address.
Leila can solve the first problem without help.
Why it works: Can shows present ability, and solve remains in its base form.
4 more examples
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Could you send the notes after the meeting?
Could makes this request more polite than a direct command.
Not this:You
can sendthe notes after the meeting. What changes: Can here says sending the notes is possible; it does not ask the person to do it. -
You should save a copy before you edit the file.
Should gives sensible advice. The listener still makes the choice.
Not this:You
must savea copy before you edit the file. What changes: Must makes the action necessary in the speaker's message. -
Visitors must show identification at the entrance.
Must expresses a rule that visitors need to follow.
Not this:Visitors
do not have to showidentification at the side entrance. What changes: Do not have to means there is no requirement. It does not mean the action is forbidden. -
The train might arrive late because of the storm.
Might shows that a late arrival is possible, but not certain.
Not this:The train
must be delayed; the platform display has stopped changing. What changes: Must can also show a strong conclusion based on evidence, rather than a rule.
Read the full guide
First decide what you mean before choosing a modal. Are you describing an ability, asking politely, giving advice, stating a rule, or naming one possible result? The meaning matters more than memorising a list of forms.
Put a modal before the base verb
Common modals include can, could, should, must, may, and might. They come before the main verb, and that verb stays in its plain base form. This pattern does not change for he, she, or it.
My brother can cook dinner for the family.
Can is followed by cook, not cooks. The subject does not add an -s after a modal.
She might join us later.
Might is followed by join, not to join or joins.
Choose the correct form: He should calls or should call the office?
Use should call. The verb after should is the base form.
Use can and could for ability and requests
Can often describes a present ability: I can read this map. Could often describes ability in the past: I could read before I started school. Both forms also appear in questions, but could usually sounds more polite when you ask someone to do something.
Can you hear the announcement from here?
This asks whether hearing is possible in the present situation.
Could you repeat the last sentence, please?
Could makes a courteous request. It does not necessarily refer to the past.
Which is more polite for a request: Can you wait a moment? or Could you wait a moment?
Both are natural, but Could you wait a moment? is usually more polite.
Give advice with should
Use should when you think an action is a good idea. It is useful for recommendations, health advice, study habits, and practical suggestions. It does not normally carry the force of an order.
You should read the question twice before choosing an answer.
The speaker recommends reading twice; the sentence does not state an official rule.
You should not share your password with anyone.
Should not gives advice against an action. The shorter form is shouldn't.
Complete the advice: If you feel tired, you ____ take a short break.
Should. The sentence gives a recommendation.
Use must carefully for rules and necessity
Must says that an action is required or very necessary. You may see it in rules, instructions, and strong personal statements. When a rule comes from an outside authority, have to is also common: We have to wear safety glasses at work.
Passengers must keep their bags with them at all times.
The sentence presents keeping bags close as a requirement.
You mustn't use your phone during the exam.
Mustn't means the action is not allowed. It is stronger than a suggestion.
Does You don't have to bring a pen mean that bringing one is forbidden?
No. It means a pen is optional. Use mustn't when an action is prohibited.
Show possibility with might
Use might when something is possible but uncertain. It is useful when you do not want to promise that an event will happen. May can have a similar meaning in more formal contexts, but might is common in everyday conversation.
I might work from home on Friday.
The speaker is considering the plan, but has not made a firm commitment.
It might not be safe to drive in thick fog.
Might not says that a safe journey is uncertain; it does not state a definite ban.
Choose the modal for uncertainty: The parcel ____ arrive tomorrow, but the tracking page is not clear.
Might. It describes a possible arrival without certainty.
Before you go
Remember this
Choose the modal for your meaning, then use the base verb. Can and could often cover ability, permission, and polite requests; should gives advice; must gives a rule or strong conclusion; might keeps a possibility open.
Practice with the written examples
You can practice with the written questions in the Learn tab. Each answer includes an explanation.
Try the written questionsListening test not available yet
This lesson does not have the recordings needed for a listening test. Use the written questions in the guide to check your understanding.
Try the written questionsQuestions about "Modal verbs: can, could, should, must, and might"
What verb form comes after a modal verb?
Use the base form of the main verb after a modal: can cook, should call, must wear, and might join. The form does not change for he, she, or it, so say She might join us later, not She might joins us later.
Leila can solve the first problem without help.
What is the difference between can and could?
Can commonly shows present ability, as in Leila can solve the first problem without help. Could can show past ability, as in Leila could solve similar problems when she was younger, and it can make a request sound more polite.
Leila could solve similar problems when she was younger.
When should I use should and must?
Use should for advice or a recommendation: You should save a copy before you edit the file. Use must for a requirement or necessary action: You must save a copy before you edit the file.
Could you send the notes after the meeting?
What is the difference between mustn't and don't have to?
Mustn't means an action is prohibited, while don't have to means it is optional. Visitors do not have to show identification at the side entrance means there is no requirement; it does not mean they are forbidden to show it.
You can send the notes after the meeting.
Does might mean something will happen?
No. Might expresses a possibility without certainty. The train might arrive late because of the storm means a late arrival is possible, while the final result is still unknown.
You should save a copy before you edit the file.
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