There are two types of auxiliary verbs and they modify/change/assist the meaning of regular and irregular verbs: a) primary auxiliary verbs b) modal auxiliary verbs

18.1 Primary Auxiliary Verbs:

There are three primary auxiliary verbs: to be, to have and to do.

18.2 Usage: Primary Auxiliary Verbs:

A: To be:

Use this verb to form the Present Continuous and Passive Tenses of regular and irregular verbs.

e.g. John is talking to Mary.

Musicians are wanted to play in the orchestra.

B: To have:

Use this verb to form the Present Perfect and Past Perfect Tenses of regular and irregular verbs.

e.g. Jane has never seen a lion.

The teacher had seen the headmaster before the class arrived.

C: To Do:

Use this verb to form questions and negative statements in the Simple Present Tense and the Simple Past Tense of regular and irregular verbs.

e.g. I do not like music by Mozart Bill did not go to work this morning.

Do you want an ice cream? Did your brothers see the Rugby match?

18.3 Structure: Primary Auxiliary Verbs:

See the relevant sections under the Simple Present and Simple Past Tenses of verbs.