1.  Twelve (12) verbs, when used as auxiliary verbs, combine with the base form only ("base form" = infinitive minus to; for example:  to go  = infinitive; go  = base form).

will would may do
shall should might does
can could must did

OK:  I will go.  You can go.  He should go.  We may go.  They do go.

Not OK: I will going.  You can gone.  He should goes.  We may went.  They do going.


2.  Seven (7) verbs, when used as auxiliary verbs, combine with present participles (base form plus ing: for example, going ) OR past participles (I have walked.  I have gone.)

                am          is             are          was        were      be           been


OK:  I am going.  He is going.  He is gone.  You are going.  You are gone.  She was going.  She was gone.  We were going.  We were gone.  They will be going.  They will be gone.  It has been going.  It has been gone.

Not OK:  I am go.  I am went.  He is goes.  He was wenting.  She will be goning.


Note:  Been  is the past participle of to be.   But, none of the 7 verbs above combines with been.  In fact, only three auxiliaries combine with been:  have, has, had.  One of these three  is always immediately in front of been  (for example:  I have been  sick.  He has been  sick.  I had been  sick.), except in the negative and interrogative (for example:  I have not been  sick. (negative)    Has he been  sick? (interrogative)).  Also Note:  Been  cannot stand alone.  For example:  Not OK:  I been  here two years.    OK:  I have been  here two years.   Not OK:  I been  living  here two years.   OK:  I have been living  here two years.


3.  Four (4) verbs, when used as auxiliary verbs, combine with past participles only.

                have       has         had         being


OK:  I have gone.  He has gone.  I had gone.  I was being robbed. 

I have chased.  He has chased.  I had chased.  I was being chased.

Not OK:  I have go.  I have going.  He has go.  He has going.  I had go .  I had going.  I was being rob.  I was being robbing.

I have chase.  I have chasing.  He has chase.   He has chasing.  I had chase.  I had chasing.  I was being chase.  I was being chasing.

NoteBeing  works best in the continuous form of passive voice, simple present and simple past only.  For example:  I am being chased (simple present).  I was being chased (simple past).   Not OK:  I will be being chased.  I have been being chased.  I had been being chased.  I will have been being chased.  I am being tired = Not OK.  I am tired = OK.    I was being lost = Not OK.  I was lost = OK.


4.  Of the 23 auxiliaries, nine (9) are auxiliary verbs ONLY.

                will          shall       can         would     should   could      may        might     must


OK:  I will go.  I shall go.  I can go.  I would go.  I should go.  I could go.  I may go.  I might go.  I must go.

Not OK:  I will here.  I shall there.  I can this.  I would that.  I should him.  I could her.  I may them.  I might it.  I must us.

Note:  Many times every day you might hear people say: I do.  She will.  He does.  We might.  You should.  They might.  I must.  It  could.   It seems  like the auxiliary  verb is being used as a principal verb, but the principal verb is not expressed.  The examples above occur only in response to questions.  Do  you like candy?  Yes, I do (like candy).  No, I don't (like candy).   Will she come here? Yes, she will (come here).  No, she won't (come here).    Does  he  study  English?  Yes, he does (study English).  No, he doesn't  (study  English).


5.  Of the 23 "auxiliaries," fourteen (14) are auxiliary verbs OR principal verbs.

                do           does       did          am          is             are          was        were     

                be           being      been       have       has         had


OK:         Auxiliary                                 Principal

                I do not like cats.                  I do my homework.

                He does like cats.*              He does a good job.

                Did you eat?**                      You did the laundry.

                I am reading.                        I am poor.

                She is not listening.            She isn't rich.

                It was running.                     It was sunny.

                We were robbed.                 We were in New York

                They will be kissed.            They will be here at noon.

                I have been studying.          I have been sick.

                I have talked to her.             I have some money.

                He has driven a car.            He has a new car.

                You had fallen down.          You had a cold.

                She was being prepared.  She was being polite.


*He does  like cats.  I do  like cats.  I did   like cats.  These sentences are in the emphatic form, and they are used only in the simple present and simple past; they are usually  responses  to statements or questions.  For example:  (1) John doesn't like cats.  Yes, he does  like cats.  John doesn't like cats, does he?  Yes, he does  like cats.    (2) You don't like cats.  Yes, I do  like cats.   You don't like cats, do you?  Yes, I do  like cats.   (3) She didn't like cats.  Yes, she did   like cats.   She didn't like cats, did she?  Yes, she did   like cats.  BUT:  If the principal verb is a form of to be , do-does-did is unnecessary.  OK:  He is rich.  Yes, he  is.  No, he isn't.  He is rich, isn't he?  Yes, he is.  No, he isn't.    ALSO:  If there is an auxiliary, do-does-did is unnecessary.  OK:  She isn't working.  Yes, she is  working.   She isn't working, is she? Yes, she is  working.

**In the interrogative and the negative, do, does, and did  are auxiliaries for the simple present and simple past--they are not emphatic.  They are not used when the principal verb is a form of to be  or when there is an auxiliary verb.  For example (principal verb is a form of to be) :  He is sick.  Interrogative = Is he sick?  Negative = He isn't sick. 

For example (an auxiliary verb):  I am talking.  Interrogative = Am I talking?  Negative =  I am not talking.