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:
| |
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. 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. |
Must (subjective obligation)
>> |
