can造句:
1.Jogging can be harmful to the health.
2.The story can’t be true.
3.Can I go now?
Yes, you can./No, you can't.
may造句:
1.She may be still waiting for us.
2.He may not come today.
3.May I go home now?
Yes, you may./No, you can't/mustn't.
must造句:
1.He must be at home.
2.You mustn't smoke here.
3.Must I clean the classroom now?
Yes, you must./No, you needn't.