Read the following sentences.
Keep to the left.
Leave at once.
Speak the truth.
Never postpone till tomorrow what you can do today.
Be regular and systematic in your work.
Forgive us our sins.
God, have mercy on us.
The first four sentences are orders or commands. Sentences 5, 6, 7 and 8 contain serious and solemn advice. The last two sentences are petitions or prayers.
A sentence which contains a command, a piece of advice or a request is said to be in the imperative mood.
The subject of the imperative sentence is generally you – i.e., the person to whom the command, advice or entreaty is addressed. It is usually omitted.
Sentences beginning with the verb let are considered to be imperative sentences. Examples are given below.
Let him go.
Let us make another attempt.
Let them try again.
Let me speak.
Sentences expressing a supposition are also said to be in the imperative mood.
Give him an inch and he will take a mile.
Take care of the pence and the pounds will take care of themselves.
Give him a chance and he will prove his mettle.
These sentences can also be expressed using an if-clause.
If you give him an inch, he will take a mile.
If you take care of the pence, the pounds will take care of themselves.
If you give him a chance, he will prove his mettle.