Shall is a modal auxiliary verb. It is followed by an infinitive without to. Shall has no –s in the third person singular.

• I shall be home soon.
• We shall invite them to dinner.
• I think I shall send him a wire.
• We shall be leaving for Delhi tomorrow.

Questions and negatives are made without do.

• Shall we report this to the police? (NOT Do we shall…?)
• No, we shall not. (NOT We don't shall.)

With the first person

In the first person shall expresses simple futurity. It is used to show the strong possibility or near certainty of an action or event which is to take place in the future.

With the second or third person

In the second and third persons shall may express a command.

• You shall go at once. (= You are commanded to go at once.)
• He shall carry out my instructions. (= He is commanded to carry out my instructions.)

Sometimes it is used to make a promise.

• He shall be given a present if he passes this year.

Shall may also express a threat.

• You shall regret this.
• They shall pay for this in due course.

Note that shall is becoming increasingly less common in Modern English. Instead of using shall in the second and third person to indicate a command, promise or threat, people often use other verbs and expressions.

For You shall go at once, people often say You will have to go at once, You are to go at once or You must go at once.

Shall: Uses

To make suggestions

Shall can be used with the first person pronouns (I or we) to make suggestions.

• You don't look well. Shall I call the doctor?
• It is very cold. Shall I close the window?
• Shall I drop you at the station?

To talk about certainty

Shall can show certainty. It is used to say that something will certainly happen, or that you are determined that something will happen.

• Don't worry. I shall be there to help you.
• She shall clean the kitchen, no matter whether she likes it or not.