Usage of may and can and must and need

May is "can" is generally used in interrogative sentences, such as may i help you?

can means "maybe" and "sometimes."

must means "certainly, must, and affirmatively.""

When need is a modal verb, the original verb is added after it, and when it is a servant verb, it is followed by the infinitive to do.

must means must, must...Affirmative: yes,..

must.Negation: Cryptophylla no,..

needn't.(In particular, it is necessary to prepare jujube injection stove rolling, sensitive, negation, and cannot use mustn.)'t.Because needn't means no, mustn't is not allowed.

For example: must i borrow the books with ID card? no,you needn't.

No, you don't. If you use no, you mustn't.It becomes "No, you don't allow it.

Finish! may means request, may....Affirmative: yes,..may.\ yes,please.\certainly\ sure...

Negative: no,..can't.\ i'm sorry ..can't.\ i'm afraid...can't.

need means need, must, need...Affirmative: yes,..must.Negative: no,..needn't.(Pay special attention to the use of affirmation.) must answer. ）

can: Yes, it's very subjective.

May: Yes, it is possible to accompany the pure staring Xu, maybe, more tactful.

must: Yes, non-negotiable, the strongest tone is hard.

should: Yes, with a strong sense of self-reproach and remorse.

must means affirmative speculation with a strong tone, and can is mostly used to negate defeat. must means affirmative, speculative tone, and can is mostly used in negation. Can is used to indicate the two tenses, simple present tense and simple past tense, and sometimes it can also indicate the future tense.

All other tenses, including the future tense, must be expressed in the infinitive to be able. Must indicates the usage of the speaker's speculation of meaning, and is used to speculate when affirming the meaning. Meaning:

It's very confusing, presumably, forgive.