English Grammar by My Teacher.

Principal Auxiliaries  / Primary Auxiliaries ar : be, do , and have



Forms of be are

• is
• am
• are
• was
• were

Forms of  do are

• do  - in present tense (plural)
• does   - in present tense (singular)
• did   - in past tense (singular/plural)

Forms of have are

• have  - present (plural) - I / you /  we / they 
• has -  present (singular)  - with he / she / it
• had - past (plural / singular)

Sentences 

I am driving a van - positive sentence
Am I driving a van - interrogative sentence
I am not driving a van - negative sentence
Am I not driving a van - negative interrogative sentence


HELPING VERBS
These include 11 primary helping verbs and 13 modal auxiliaries.
The primary auxiliaries (be, do , and have ) are to express a fact
   
The modal auxiliaries  are to express a mood or attitude.
(will, would), (shall, should), (can, could), (may , might), aught to, need to, dare to, used to, have to, must.

HAVE -  used to express possession, relations, illness, some thing late etc.
I have a dinner  - present
I had a dinner - past




Some usages and meanings 
put on (wear) ,
put off (postpone), 
put up (temporary stay) - where are you putting up / where you have been putting up
get on
get off
get up


After modal verbs we can use only the base form (present) of verbs.
Question word must followed by a helping word's present tense form.
    What can we say now ?  -is a valid statement
    What we say now ?  -is an invalid statement

I have a dinner - present
I had a dinner -

Questions - 

1.  yes / no 
2. who, what, where, when, why, which, whom, whose, how.