Writing Skill and Proofreading

Necessary' is correct.

People' is plural, requiring 'are'.

Indefinite pronouns like 'everybody' are singular.

You' requires 'are'.

Maintenance' is correct.

Either/or' agrees with the nearest subject ('students'), which is plural.

Apples' is plural, requiring the plural demonstrative 'These'.

Its' is the possessive pronoun; 'it's' is 'it is'.

Definite' is the correct spelling.

Subject pronouns ('He' and 'I') are required for the subject of the sentence.

The subject is 'books' (plural).

Prettier' is the correct comparative form.

Have gone' (past participle) is the correct perfect tense form.

News' is an uncountable, singular noun.

Well' is the adverb modifying 'writes'. 'Does' matches the singular subject 'she'.

You' is a plural pronoun (or used with plural verb forms), so 'are' is correct.

Could have' is the correct auxiliary verb construction.

Necessary' is the correct spelling (one 'c', two 's's).

Along with his friends' is a prepositional phrase, so the subject remains 'brother' (singular).