Explain English grammar topic Models

Modals are auxiliary verbs used to form the tenses, moods, voices, etc. of other verbs. They are helping verbs that cannot be used on their own but to be used along with other main verbs mainly to express attitudes.
1. When something happens, they form a tense of the main verb.
Examples:

• I shall go.
• He was going

2. They express permission, necessity, or possibility to do something.
Examples:

• They may go.
• You must go.
• I can’t go.
• I might go.
• She would go if she could.

Observe the highlighted words in these sentences.

• We can make our nation a superpower by the year 2020.
• Kalam says that we need to do things ourselves. We must not import equipment from other nations.
• In twenty years, each one of us ought to have our destiny worked out.

All the highlighted words are Modal Auxiliaries that are used with another verb, and express the mood of the speaker.

• The main MODALS are: can, could; may, might; shall, should; will, would; must; ought to; need to; have to.
• The negative modals are: couldn’t, wouldn’t, shouldn’t, mustn’t, needn’t, oughtn’t.