Modal verbs are verbs such as can, may, must, need not, shall/should/ought to. They indicate ability, permission, etc.
Example: Vijay is 15 years old and wants to become a mechanic. He is going to take over his father’s garage, so he need not worry about his future. Vijay’s father tells him every day that he must do what he is told and must not touch any dangerous equipment. Vijay can already change tyres, but he has to learn a lot more about cars. He should work in the garage more often if he wants to be a good mechanic.
1. Modal verbs are generally only used in the present tense. In the third person singular, we don’t add an s.
Vijay must do what he is told. (not: he musts)
For negation, we don’t need to add a helping verb.
Vijay need not worry about his future.
Vijay must not touch any dangerous equipment.
need not means do not have to AND must not means be not allowed to
2. Modal verbs are always used along with a full verb (except for short answers and question tags). The full verb is added without to.
Vijay can change tyres. (not: Vijay can to change tyres.)
Common Modal Verbs
Must/ Ought to