"Has/Have/Had" as a main verb and auxiliary verb
I need help regarding the use of has/have/had both as a main verb and as an auxiliary verb.
In the sentence below, the word has acts as the main verb. I would normally follow it with the phrase "so do I."
- Kenny has a car, and so do I.
On the other hand, the word has in the following sentence acts as an auxiliary verb. I would normally follow it with the phrase "so have I."
- Kenny has bought a car, and so have I.
a) Are sentences 1 & 2 above correct? I'm under the impression that so do I is used when has/have/had is the main verb of a sentence, and so have/had I if it's an auxiliary verb in a sentence.
b) Does the verb has/have always need a supporting "auxiliary verb" (either implied or mentioned)? (e.g., Kenny has a car = Kenny does have a car.)
Yes, 1 and 2 are correct. You've got the right idea about this.
No, there is no implied auxiliary verb in b) , nor in 1. There are two distinct uses of "have". One is as an auxiliary verb; the other means "to own" (or several variations, such as "have a good time). These latter senses need no auxiliary verb, except when forming present perfect (e.g. "He has had that car for years.") or past perfect (e.g. "He had had a good time at the party, until she spilled cola on his pants.")
Let's start with "is", which is always an auxiliary verb, even when there is no main verb for it to be auxiliary to. It always inverts in yes-no questions, whether it's part of the progressive, part of the passive, or the copula: "Is he leaving?" "Is he admired?" "Is he intelligent?"
For some English speakers, "has" is like this, also. It inverts whether it is part of the perfect or the possessive "has" (though I'm not sure about causative "have"): "Has he left yet?" "Has he a wool sweater?" ???"Has he Henry come home before 7?" For this dialect, corresponding to your example 1, we'd get "Kenny has a car, and so have I." This is the English of the nursery rhyme "Baa, baa, black sheep, have you any wool?"
For other English speakers, only the perfect "has" inverts like an auxiliary: "Has he left yet?" "Does he have a wool sweater?" "Does he have Henry come home before 7?"
Some English speakers can use "have" either way.