Summary: Subject Verb Agreement

• Subject

Subject is the person/people/thing(s) that do the activity.
Example : I, you, they, we, she, he, it, my dad and my mom, Linda and Susi, the bank, the flight schedule, etc.

• Verb

Verb is a word used to describe an action, state, or occurrence, and forming the main part of the predicate of a sentence.

Kinds of verb :

• Action Verb

Also known as MAIN VERB.
Action verbs are words that express action (give, eat, walk, etc.) or possession (have, own, etc.). 
Action verbs can be either transitive (with object) or intransitive (without object). 
Example : Laurissa rises slowly from her seat.

• Linking Verb

A linking verb connects the subject of a sentence to a noun or adjective that renames or describes the subject.
To be : is, am, are, was, were.

Example : We were there!

Verb: seem, appear, become, grow, remain, get, prove, turn, look, sound, smell, taste, feel.

Example : That sounds great!

• Helping Verb

Helping verbs are used before action or linking verbs to convey additional information regarding aspects of possibility (can, could, etc.) or time (was, did, has, etc.) 

Modals always function as Helping Verbs.

Modals = can, could, may, might, shall, will, ought to, should, would.

Example : The trip might (helping verb) be (main verb) dangerous.

• MAIN RULE OF "Subject Verb Agreement"