As a modal verb can ‘have to’ have an ‘ing’ form?
Hello again, Symphony,
Have to is what is called a "periphrastic modal"; it is not a full-blooded modal like will, would, shall, should, may, might, can, and could. Indeed, have to can be used in combination with those other modals:
- He will have to work very hard.
- She shouldn't have to go.
- They may have to work overtime.
Have to can certainly be used in its ing form having to. Having to is commonly used both as a gerund and as a present participle, depending on the syntactic context. Below is an example of each:
- participle: He has been having to help her out a lot lately.
- gerund: He hates having to wake up so early.
The verb after ‘have to’ is used in base form only, right?
No. As you can see, having to is also used, both as a present participle and as a gerund. Have to also has the past-tense and past-participle form had to (He had to / has had to help out a lot) and the third-person singular present formhas to.