Use modal auxiliary verbs can, may, must in positive or negative forms (can't, mustn't, needn't).
Good morning, Madam. ___ help you?
Can I help you?
I'll take care of her. You ___ worry.
You need not worry.
Can May Must
Exercises with answers, PDF worksheets and grammar rules with examples.
1. The opposite of can is cannot (can't).
I can speak Polish fluently.
I cannot speak Polish at all.
You can use my laptop. I don't need it now.
You can't use my laptop. I need it now.
2. The opposite of may is must not (mustn't).
May I kiss you, Betty.
No, you mustn't. Are you kidding?
OK. You may go to the disco tonight.
You mustn't go to the disco tonight. You're grounded.
3. The opposite of must is need not (needn't).
I must help you with the housework.
No, you needn't. I'll do it on my own today.
You must read the instructions first.
No, I need not. I know how to do it.