Helping verbs

Helping verbs are verbs that are used in a verb phrase (meaning, used with a second verb) to show tense, or form a question or a negative.   Helping verbs are used to show the perfect verb tenses, continuous/progressive verb tenses, and passive voice.  Helping verbs are always followed by a second verb.   
When using helping verbs to show tense, the sentence pattern will be: 

SUBJECT
--->

 HELPING VERB
--->

 VERB 2
---> 

 THE REST OF THE SENTENCE

(noun, pronoun, or noun phrase)

(verb)

 (second verb) (adj, adv, noun, prepositional phrase, etc.)
When using helping verbs to form a question, the sentence structure will be:

HELPING VERB
--->

 SUBJECT
--->

 VERB 2
---> 

 THE REST OF THE SENTENCE

(verb)

(noun, pronoun, or noun phrase)

 (second verb) (adj, adv, noun, prepositional phrase, etc.)

There are three categories for helping verbs: "do, be, have," modals, and two-word modals.

DO BE, HAVE:  they help other verbs make questions, negatives, and some verb tenses. Remember--  DO, BE, and HAVE are only helping verbs when they are used with a second verb.

DO is a helping verb when it is used to indicate questions, negatives, and emphasis.
Questions with DO Do you have a car? These sentences are in question form.  Do/Does/Did are used as helping verbs with have to make these sentences questions.   
Does he have a car?
Did he have a car before?
Emphasis with DO I do want to go to the park. If you were responding to a statement like, "You don't want to go to the park" you may want to reply with great emphasis. Situations like that are perfect for using Do/Does/Did to show you really mean something. In these sentences Do/Does/Did are used with the verb want.
He does want to go to the park.
They really did want to go to the park.
Negatives with DO I do not want to go to the zoo. Do/Does/Did are used as helping verbs to form a negative. In these sentences they are used with want.  The word not forms a negative response for each sentence.
He does not want to go to the zoo.
They did not want to go to the zoo.
BE is a helping verb when it is used to form the continuous/progressive tense or to show passive voice.
Continuous tense with BE I am helping Diane right now. These sentences use Am/Was/Will Be (forms of the verb BE) to form the continuous verb tense. Am/Was/Will Be are used with the verb helping.
I was helping Diane when George paged me.
I will be helping Diane when George comes home.
Passive voice with BE The picnic is being canceled because of rain. These sentences use Is/Was/Will Be with the second verb completed in order to show passive voice.
The picnic was canceled because of rain.
The picnic will be canceled because of rain.
HAVE is a helping verb when it is used to show the perfect verb tenses, or used to form a question.
Perfect tense with HAVE I have studied French for two years. These sentences use have/had with the second verb studied to show the perfect tense.
I had studied French for two years before I went to Paris.
I will have studied French for three years in August.
Questions with HAVE Have you seen that new movie yet? Have is used with the verb seen to make a question.

 

Another kind of helping verb is called a MODAL.  
Modals are a special kind of helping verb that do not show tense and do not follow subject/verb agreement. They do not add 's' in the third person singular (he, she, it). They are not conjugated. They are used to show possibility, probability, and necessity. Like other helping verbs, modals are always followed by a second verb.  But the second verb must follow a different conjugation pattern if a modal is present.  The second verb can never add -s, -es, -ed, or -ing.  It also cannot be in the infinitive form (to...) or in the gerund form (...-ing).
When using modals, the sentence structure will be:

SUBJECT
--->

  MODAL
--->

 VERB 2
---> 

 THE REST OF THE SENTENCE

(noun, pronoun, or noun phrase)

(should, would, could,may might, etc)

 (second verb) (adj, adv, noun, prepositional phrase, etc.)

 

Here are some common one-word MODALS:  these express probability, possibility, necessity, and "if . . . would" situations

could shall should
might can must
may would will

Here are some common TWO-WORD MODALS:  These also express probability, possibility, and necessity, but two-word modals use the word 'to.'


used to
have to
have got to
ought to

Here are some examples of modals in sentences:

We can leave when you are ready. 'Can' is a modal that is part of the verb phrase, "can leave." It means that we are able to leave when you are ready, but that it is not necessary that we leave.
Bob will want to meet Sue. 'Will' is a modal that must be part of the phrase "will want." It shows that Bob definitely wants to meet Sue.
Greg might play soccer. 'Might' is a modal that is part of the phrase "might play" in this sentence.  The word might indicates that there is a chance that Greg will play, or that he won't play soccer.
They have to finish their dinner before they can watch T.V. 'Have to' is a two-word modal in this sentence. It means that they are required to finish their dinner before they can watch T.V.