The Indicative Mood shows that the action or state expressed by the verb is presented as a fact.

We went home early in the evening. (Dickens)

The Indicative Mood is also used to express a real condition, i. e. a condition the realization of which is considered possible.

If it rains, I shall stay at home.
If Catherine disobeys us, we shall disinherit her. (Eliot)

The Imperative Mood expresses a command or a request. In Modern English the Imperative Mood has only one form which coincides with the infinitive without the particle to; it is used in the second person (singular and plural).

Be quiet and hear what I tell you. (Eliot)
Please put the papers on the table by the bed.(Hemingway)

In forming the negative the auxiliary verb to do is always used, even with the verb to be.

Hush! Don’t make a noise! (Eliot)
Don’t be angry… (Hemingway)

The auxiliary verb to do may also be used in affirmative sentences to make the request more emphatic.

But now, do sing again to us. (Eliot)

To make a request or an order more emphatic the subject expressed by the pronoun you is sometimes used. It is characteristic of colloquial speech.

I’ll drive and you sleep awhile. (Hemingway)

A command addressed to the third person singular and plural is usually expressed with the help of the verb to let.

Let the child go home at once.
Let the children go home at once.

With the first person plural the verb to let is used to express an exhortation to a joint action.

Let’s go and have some fresh coffee. (Mansfield)

The Subjunctive Mood shows that the action or state expressed by the verb is presented as a non-fact, as something imaginary or desired. The Subjunctive Mood is also used to express an emotional attitude of the speaker, to real facts.

In Modern English the Subjunctive Mood has synthetic and analytical forms.

“I wish I were ten years older,” I said. (Braine)
I wish you would speak rationally. (E. Bronte)