here´s a further explanation for modal verbs. I hope it´s a bit clearer and more useful. Exercises at the bottom of the post!
Used to express ability (to be able to do something):
- I can make jewelry.
- He can’t speak French.
- Can you open this jar?
Used to ask for permission:
- Can I use your bathroom?
- Can I leave now?
- Can I raise the volume?
Used to make requests or suggestions:
- Can I have more napkins?
- Can I have the bill?
- You can take this spot if you like.
- You can do whatever you want.
Could (past form of can)
Describes an ability that someone had in the past:
- I could swim when I was young.
- You could see the boat sinking.
- They could tell he was nervous.
Often used in auxiliary functions to express permission politely:
- Could I take this jacket with me?
- You could borrow my umbrella.
- Could you please let me pass you?
- Could I get you more water?
Used to express possibility:
- All of them could ride in the van.
- You could always stay at our house.
- Could it be true?
- This plan could really work out.
Used to ask for formal permission:
- May I come in?
- May I say something now?
- May I ask one question?
Used to suggest something that is possible:
- She may agree with this plan.
- They may not be happy about what happened.
- It may shower tonight.
Might (past form of may)
Used to suggest a smaller possibility than may does (actually, might is more common than may in American English):
- He might have finished it.
- I might go see a doctor.
- I might not come this time.
- It might be right.
- You might have lost it.
- The store might have been closed today.
Used to express something formally required or necessary:
- I must complete the project by this week.
- The government must provide health care for everybody.
- Everyone must save the natural resources of the earth.
- The building must have a fire alarm.
- You must answer my question right now.
Used to show that something is very likely:
- He must be a genius.
- You must be joking!
- There must be an accident.
- She must be very tired.
“Have to” is used to express certainty, necessity, and obligation.
- This answer has to be correct. certainty
- The soup has to be stirred continuously to prevent burning. necessity
- They have to leave early. obligation
Choose the right word for each blank.
1) She (can, could, may, might, must) have practiced a lot. Her performance was amazing.
2) I can’t find my watch anywhere. I (can, could, may, might, must) have lost it.
3) Professor, (can, could, may, might, must) I ask a question?
4) (can, could, may, might, must) you please lower your voice?
5) You (can, could, may, might, must) be kidding! How is that possible?
6) I (can, could, may, might, must) speak both English and Chinese fluently.
Follow these links for further practice: