Why do we add S to some words but ES to others? And when a word ends with Y, how do we know whether to change the Y to I before adding the plural suffix? And why on earth does knife become knives? You can unravel these mysteries with six simple rules.
Subjects and verbs must agree in number. This is the cornerstone rule that forms the background of the concept. The dog growls when he is angry. The dogs growl when they are angry. 2. Don’t get confused by the words that come between the subject and verb; they do not affect agreement.