Modal Auxiliaries: are like Modal verbs They facilitate the main verb for suggesting potential, expectation, permission, ability, possibility, and obligation.
When used with the main verb, modal verbs do not end with –s for the third-person singular. Modal auxiliary verbs never change the form, but they have a different form for past tense.
The modal auxiliaries include:
| Present Tense | Past Tense |
| Will
Can Must (have to) May Should (ought to) (had better) |
Would (used to)
Could (Had to) Might Should (ought to) |
Will – Would:
Will indicates a ‘willingness’ to do something in the future. The negative form of will – will not (won’t) indicates an ‘unwillingness’ (refusal, reluctance) to do something.
Examples:
- I will give you a different book.
- I will attend that function.
- They will arrive today.
- She won’t come tomorrow.
Would indicate general or repeated willingness in the past. It also indicates preference in the present.
Examples:
- If you did work, I would take you with me.
- Whenever I had to go to a new city, they would pack my bags.
- I thought he would buy this book.
Can – Could – May – Might: Can indicates ability. Could indicates ability with an option.
Examples:
- I can do it the whole day. (The subject ‘I’ is sure about his/her ability)
- I could do it in a better way. (The subject ‘I’ is not sure about his/her ability)
- They cannot do it on time. (present)
- They could not do it on time. (past)
Can & could also indicate possibility.
Examples:
- The temperature can rise by the end of the day.
- They can’t go too far just for ice cream.
- It could rain now.
May and might both indicate possibility but might suggest that there is less possibility than may.
Examples:
- It may rain continuously for four more days.
- It might rain right now.
- They may come back right now.
- They might come back.
Must: Must indicate necessity.
Examples:
- I must leave tonight.
- She must work on it.
- you must go home by 6.00 pm.
Have to: has a similar meaning to must but implies less urgency.
Examples:
- I have to leave now.
- He has to study hard.
- Alex has to go by 6.00 pm.
- I had to leave then. (past)
- He had to study hard to pass the exam. (past)
Should: Should indicates obligation and probability.
Examples:
- You should come on time.
- You should not go there at all.
- I should visit the hospital regularly.
- There should be an extra space for the shoe rack(probability)
- He should have reached on time. (probability)
- I should have done that before only. (obligation in the past)
Ought to and had better sometimes replaces should.
Examples:
- You ought to come to the party on time.
- We ought to have taken a taxi after leaving home. (Past)
- We had better leave. (Had better is generally used in spoken English.)
- I think parents ought to give children more freedom. (Had better won’t be appropriate here.