Change the following sentence into a negative one: This boy plays football.

Concept

To negate a verb in the simple present tense (other than "to be"), English inserts the auxiliary do/does before not, and the main verb returns to its base form. The auxiliary carries the tense and number, so the main verb sheds its third-person "-s".

Applying it to this sentence

• Subject: "This boy" is third-person singular, so the auxiliary is does (not "do").

• Add not after the auxiliary: "does not".

• Return the main verb to its base form: "plays" → "play".

• Result: This boy does not play football.

Why the other forms fail

• "This boy not plays football." — no auxiliary, so there is nothing to carry the negation.

• "This boy no plays football." — "no" negates a noun, not a finite verb.

• "This boy do not plays football." — "do" disagrees with the singular subject, and "plays" should be the base "play".