Ruth,

I thought you might benefit from looking at the analysis of the English verb
and auxiliary from the generative transformational perspective.  This one
comes from my text.  It mostly follows early GT theory.   Like any
analytical system for grammar, it has a few flaws and frustrations. Notice
that it isn't much like traditional conjugation.  For instance, the only
tenses mentioned are past and not past (or present).  The formula is
descriptive of the verb in the normal order, active voice, declarative
sentences.  I find it useful for students who have not studied traditional
conjugation.  It is a more direct route to the understanding of the English
verb than memorization of a whole list of tenses, modes, and voices that
even we who teach grammar have a hard time remembering.

Elaboration of the Auxiliary.

Before we begin our discussion, you need the formula:

T + (Modal) + (Have + EN) + (BE + ING) + MV

Note #1:   The last item in the formula, MV, stands for main verb which is,
technically, a different constituent from the auxiliary. I include it in the
formula for the sake of convenience and clarity.

Note #2:  Only two items in the formula are not in parentheses. Remember
that parentheses in this kind of formula mean that the item is optional.
Thus, since the MV is not part of AUX, the only component of AUX that is
required in a finite clause is the T: tense.

Note #3:  The above formula is for finite clauses. For nonfinite VPs, omit
T.

Note #4:  We are dealing here only with simple sentences that occur in the
forms of the unelaborated basic sentence patterns. Used in other sentences,
slight differences occur in the formula which we will not go into at this
time. Just as and example, the auxiliary verb "do" might be present.

Now, can we talk?

First, the outline of the basic components of the formula:

T for Tense. There are only two tenses recognized by the formula: Past and
Not Past. (I am the only grammarian I know of who refers to this as "not
past." Expect to see it in other texts as "present." Maybe someday, I'll
convince a disbelieving world!  Or they'll convince me.) The tense is
attached to the first verb word in the VP.

Modal.  We have quite a list. Memorize it. Can, could, will, would, shall,
should, may, might, must. The modal, if it occurs, is the first word in the
AUX. Therefore, if it occurs, it carries tense (past or not past). Can,
will, shall, and may are Not Past. Could, would, should, and might are Past.
Must is fuzzy in terms of tense and not a problem.

HAVE. Three forms exist: have, has, had. If there is no modal and there is a
HAVE, it carries tense (past or not past).

EN. This represents the morpheme that is always present on the next word in
the AUX/Verb after the HAVE word if the HAVE word is present. Note that it
is not attached to HAVE. It is placed by HAVE in the formula because it
always goes in partnership with HAVE. Also, EN will not always be
spelled -en. Sometimes it will be spelled -t or -ed or some other spelling.
The language is not absolute in this regard.

BE. Six variations occur: be, am, is, are, was, were.  Notice that been and
being are not on the list.  That's because the -en on been refers back to
HAVE as noted above.  The -ing on being will only be there if be is the main
verb, if the sentence is in passive voice (see Chapter 19), or in some other
construction that does not reflect a basic sentence pattern.

ING. Like the EN after HAVE, this ING is always attached to the next
AUX/Verb after the BE.

Note:  Remember that both have and be can serve as main verbs.   In that
case, they are not part of AUX, and different rules apply.

MV. I told you about this above.

Now, some sample sentences. For now, we'll use only Pattern #1 sentences.
The other patterns are no more complicated and entail no additional
learning, but we'll avoid confusion for now by using only Pattern #1.  In
brackets after the sentences, I have provided the parts of the verb formula
that apply.  Also, I have put all of the parts, including EN and ING in the
order of their occurance in the sentences, not in the order of occurance in
the basic formula.  Finally, notice that there are no parentheses.

My cat eats. [Not Past + MV]

My cat ate. [Past + MV]

My cat can eat. [Not Past + Modal + MV]

My cat could eat. [Past + Modal + MV]

My cat could have eaten. [Past + Modal + HAVE + MV + EN]

My cat had eaten. [Past + HAVE + MV + EN]

My cat might have been eating. [Past + Modal + HAVE + BE + EN + MV + ING]

My cat might be eating. [Past + Modal + BE + MV + ING]

My cat was eating. [Past + BE + MV + ING]

Jeff Glauner
Park University