The correct answer is "She studies English every day". The subject She is third person singular, so the verb must end with s. The time marker every day indicates present simple tense.

The correct answer is "Went". The word yesterday indicates a completed past action, so the past tense went is correct.

The correct answer is "I saw an elephant at the zoo". The word elephant begins with a vowel sound, so the article an is used.

The correct answer is "The students are preparing for the exam". The subject students is plural, so the verb must be are.

The correct answer is "She has completed her assignment". The present perfect tense is formed with has or have plus the past participle.

The correct answer is "In". The correct preposition after interested is in. He is interested in science.

The correct answer is "She don't like coffee". The subject She is third person singular, so the negative auxiliary should be doesn't, not don't.

The correct answer is "This book is more interesting than that one". For adjectives with two or more syllables, the comparative form uses more plus the adjective.

The correct answer is "After the meeting, we went for lunch". A comma is correctly placed after the introductory phrase "After the meeting".

The correct answer is "The report was written by the manager". The passive voice uses the past participle written after the appropriate form of to be was.

The correct answer is "If it rains, we will stay indoors". This is a first conditional sentence: if plus present simple, then will plus base verb.

The correct answer is "Neither of the answers is correct". Neither is singular, so it takes a singular verb is.