let us learn how to use can, could, may, might, should, ought, must, have to, shall, will, or would. These are modals and they determine the mmod of the speaker. Some negative modals are couldn’t, wouldn’t, shouldn’t, mustn’t, needn’t, oughtn’t.
1. Don’t change its form and turn it into the present, future, or past forms.
2. Use the base form of the verb after a modal don’t use “to” or the full infinitive verb “to”
3. To use modals in the negative form, use only “not” AFTER the modal verb.
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MUST expresses strong obligation. Negative of must is mustn't, it is used in the sense of prohibition: You must be at the railway station at 3PM to meet the guests.
MUST is used to express compulsion: You must return before 11pm from the party.
MUST is used to offer suggestion: You must consult a good doctor immidiately.
HAVE TO expresses strong obligation, it expresses external obligation: You have to come on time if you don’t want to miss the office bus.
HAVE TO is used to express supposition in future. You will have to work very hard to upgrade your scores.
WILL is used to state a promise: I will stop eating sugary and salty foods as my sugar level has been increased.
SHALL expresses suggestion as used in the first person: Shall I offer you a cup of green tea?
WOULD shows habits in the past: He would visit nearby tample every Monday.
WOULD is used for a polite request: Would you close the windows, please?
CAN shows ability: He can speak French fluently.
CAN shows permission: Can I use your pen?
CAN shows possibility: Fast driving in foggy night can cause an accident.
COULD expresses possibility: You could do it, if you tried hard.
COULD is also used to ask polite questions: Could you, please, pass me the salt?
MAY expresses permission: May I borrow your umbrella?
MAY is used to pray to God for some wish: May he live long.
MIGHT conveys possibility: I might move to Delhi next year.
SHOULD is used for giving advice: You should revise the intro to your article.
OUGHT TO is used to offer logical conclusion: After driving all day, you ought to be tired.