Unit 05. HAVE TO

Have to

Have to is NOT an auxiliary verb (it uses the verb have as a main verb). We include have to here for convenience.

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

Have to is often grouped with modal auxiliary verbs for convenience, but in fact it is not a modal verb. It is not even an auxiliary verb. In the have to structure, "have" is a main verb. The structure is:

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

Look at these examples in the simple tense:

+ 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. Look at these examples:

* In France, you have to drive on the right.
* In England, most schoolchildren have to wear a uniform.
* John has to wear a tie at work.

In each of the above cases, the obligation is not the subject's opinion or idea. The obligation is imposed from outside.

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.

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