Have to

Have to (objective obligation)

We often use have to to say that something is obligatory, for example:

• Children have to go to school

Structure of Have to

subject + auxiliary verb + have + infinitive (with to)

Look at these examples in the simple tense:

	subject	auxiliary verb	main verb have	infinitive (with to)
+	She		has	to work.
-	I	do not	have	to see	the doctor.
?	Did	you	have	to go	to school?

Use of Have to

In general, have to expresses impersonal obligation. The subject of have to is obliged or forced to act by a separate, external power (for example, the Law or school rules). Have to is objective. example:

• John has to wear a tie at work.

We can use have to in all tenses, and also with modal auxiliaries. We conjugate it just like any other main verb. Here are some examples:

	subject	auxiliary verb	main verb have	infinitive
past simple	I		had	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.

NEEDN'T HAVE AND DIDN'T NEED TO

NEEDN'T HAVE AND DIDN'T NEED TO

Both these forms are used to talk about past events, but there is sometimes a difference in use. When we say that someone needn't have done something, it means that they did it, but it was not necessary. Didn't need to is also sometimes used in this way:

 

Examples:

-You needn't have washed the dishes. I would've put them in the dishwasher.

ª      - I needn't have prepared all that food. They phoned to say they wouldn't be coming.

ª      - We had plenty of petrol in the tank so I didn't need to fill up.

ª      - We didn't need to wait for long for them. They arrived just after us.