Auxiliary Verb Forms

Modal Auxiliaries

Have

Be

Do

can
could
will
would
shall
should
may
might
must

have
has
had
having

am
is
are
was
were
been
being

do
does
did
done
doing

1. Modal auxiliaries always precede the main verb, as well as any other auxiliaries that are present.
2. Modal auxiliaries cannot be made negative.
3. Have always occurs before the past participle (-en) form of another verb to express the perfect (completed) aspect of the verb. When have is in the present tense, it creates the present-perfect form of the verb.
   NOTE: Have can also function as a true verb, having different meanings (i.e., Kelly has the book.).
4. Be is used to express the progressive (ongoing) aspect of the verb or the past-progressive form when be is in the past tense.
   NOTE: Be can also function as a true verb, having different meanings (i.e., The gas station is open.).
5. Do is in a number of grammatical processes. Use do when you create certain kinds of questions.
6. Do is also used to form negatives and emphatic statements.