Correct Answer: A

Rationale: The correct answer is A. 'Ain't' is not grammatically correct in formal writing or speech; it should be 'isn't.' 'Ain't' is considered slang and is not appropriate for formal contexts. The other choices ('During,' 'Sure,' 'Playoff') are used correctly in the sentence.

Correct Answer: A

Rationale: The correct answer is 'bilateral.' 'Bilateral' means having two sides or affecting both sides. 'Insufficient' means not enough or inadequate, 'bicuspid' refers to a two-pointed tooth, and 'congruent' means in agreement or harmony. Therefore, 'bilateral' is the only word among the choices that specifically relates to being on both sides.

Correct Answer: C

Rationale: The correct answer is 'C: Hers.' The possessive pronoun 'hers' does not require an apostrophe. The use of 'her's' with an apostrophe is grammatically incorrect. Choices A, B, and D ('Backpack,' 'Student,' and 'Recognize') are all spelled correctly and are grammatically sound in the sentence provided.

Correct Answer: A

Rationale: The correct answer is A: 'Is.' In this sentence, 'Economics' is being treated as a singular subject, so the verb should also be singular. 'Is' is the correct singular form of the verb to agree with the singular subject 'Economics.' Choice B, 'Been,' is incorrect because it is the past participle form of the verb 'be' and does not agree with the singular subject 'Economics.' Choice C, 'Am,' is incorrect because it is the first-person singular form of the verb 'be' and does not agree with the singular subject 'Economics.' Choice D, 'Are,' is incorrect because it is the plural form of the verb 'be' and does not agree with the singular subject 'Economics.'

Correct Answer: C

Rationale: The correct answer is 'C: Laid.' 'Laid' is the correct past tense form of 'lay,' which means to put something down. 'Layed' in choice A is incorrect as the past tense of 'lay' is 'laid,' not 'layed.' Choice B, 'Drop,' is incorrect as it does not fit the context of placing something on the table. Choice D, 'Lay,' is the base form of the verb and does not fit the sentence in the past tense.