Must and Ought to - Grammar short Lesson

Must doesn’t change its form, whatever be its tense or the number and person of its subject. It can refer to the present or future.
    You must do this now. (Present)
    He must pay damages. (Future)
    You must file a petition. (Future)

May and Might - Grammar short Lesson

May is used to ask for permission.
    May I come in, please?
    May I go home now?
May not is used to deny permission.
    ‘May I go now?’ ‘No, you may not.’

Would Uses - Grammar short Lesson

Would is the past tense of will in indirect speech.
Direct: The manager said, ‘The shop will be closed on Monday.’
Indirect: The manager said that the shop would be closed on Monday. >>> Read More.

Should Uses - Grammar short Lesson

Should is the past tense of shall in indirect speech.

    Direct: He said, ‘the scoundrel shall be trashed.’
    Indirect: He said that the scoundrel should be trashed.
>>> Read More.

Uses of shall and will - Grammar short Lesson

With the first person
The modal auxiliary verb shall is used with first person pronouns to express the strong possibility or near certainty of an action which is to take place in the near future.>>> Read More.