A verb phrase is made up of the main verb and any helping (or auxiliary) verbs. For example, in the sentence "The cat is walking across the piano," "walking" is the main verb, while "is" is the helping verb. A helping verb works with, or "helps," the main verb.

It should be noted that certain verbs can be main or helping verbs. For example, in the sentence, "She is at the store," "is" is the main verb, but "is" is the helping verb in the example sentence I gave earlier ("The cat is walking across the piano.") The main helping verbs are forms of to be, such as am, is, are, was, were, be, been, and being; forms of do, such as do, doing, done; and forms of have, such as have, has, and had. In addition, some helping verbs are modal verbs, which, unlike the other helping verbs, do not change forms. Modal verbs include can, could, will, would, shall, should, must, may, might, and ought.

First, be sure to understand what a phrase is.  The phrase is one or more words without a subject and verb together.  A phrase cannot stand by itself. 

Sometimes a sentence can communicate its meaning with a one-word verb. Sometimes it is necessary to use two or more words in the verb.  All of these are called a verb phrase.  The verb phrase may include helping or auxiliary verbs and modal verbs. The two things are:

• modifying verbs (auxiliary/modal) + main verb head word

Here are some examples of verb phrases in italics and explanations at the end:

• She was walking to the mall. 
• Ted might eat the cake.
• You must go right now. 
• Words were spoken.
  
• The teacher is writing a report.

• She came across some old love letters.
• The small dog was reluctant to learn new things.
• Finally, we can afford to buy a new house. (afford to: phrasal verb)
• Walking on the ice, she slipped and fell.
• Open the door to let the fresh air in.