Verb Phrases

A verb phrase is made up of a main verb and one or more helping verbs. 
A main verb can stand by itself as the simple predicate of a sentence while the helping verb cannot.

A helping verb (also called an auxiliary verb) is a verb that is used together with the main verb of the sentence to convey the action, so it helps the verb be more precise. The helping verb will often be a form of the verb (to be), or the verb (to have) or the verb (will) to show action in the future. When there is a helping verb, the main verb is often a gerund (a form of the verb that ends in –ing) or a past participle (a form of the verb which often ends in –ed, –n, or–en). 

On the other hand, the linking verb is a verb that connects the subject with an adjective or a noun that describes it.

Example: Anna got mad (the linking verb got connects the subject Anna with the adjective mad.

The student has been writing essays all day.                                                                                       (Helping verb: has been; Main verb: writing)   

Amanda may run in the park.                                                                                                                  (Helping verb: may; Main verb: run)

The man has gone.                                                                                                                              (Helping Verb: has; Main verb: gone)

Did you throw it?                                                                                                                                 (Helping Verb: did; Main Verb: throw)

Helping Verbs:
Be     Am        Is       Are      Was      Were      Being     Been
Have  Has     Had     Do       Does     Did        May       Might 
Must   Can   Could  Shall     Will     Should   Ought    Would