to work

yesterday. present simple I

have

to work

today. future simple I will

have

to work

tomorrow. present continuous She is

having

to wait.

present perfect We have

had

to change

the time. modal (may) They may

have

to do

it again.

Must (subjective obligation)

We often use must to say that something is essential or necessary, for example:

• I must go.

Structure of Must

"Must" is a modal auxiliary verb. It is followed by a main verb. The structure is:

subject + must + main verb

The main verb is the base verb (infinitive without "to").

Look at these examples:

subject	auxiliary verb "must"	main verb
I	must	go	home.
You	must	visit	us.
We	must	stop	now.

Use of Must

In general, "must" expresses personal obligation. "Must" expresses what the speaker thinks is necessary. "Must" is subjective. Look at these examples:

• I must stop smoking.

• You must visit us soon.