Which of the following sentences uses a comma correctly?

Correct Answer: B

Rationale: The correct answer is B: 'Let's eat, Grandma!' The comma is correctly used to separate the direct address 'Grandma' from the rest of the sentence. In choice A, there should be a comma after 'eat' to separate the direct address. Choice C is missing an apostrophe in 'Lets,' and there should be a comma after 'eat' to separate the direct address. Choice D incorrectly places a comma after 'Lets,' and there should be a comma after 'eat' to separate the direct address.

Correct Answer: B

Rationale: The correct answer is B: 'Before.' The prefix 'pre-' means 'before,' indicating something that comes before the main action or event. For example, in words like 'preview' or 'predict,' the prefix 'pre-' implies anticipation or happening before the complete action. Choices A, C, and D are incorrect. 'After' (Choice A) is the opposite of 'before,' 'During' (Choice C) implies something happening at the same time, not before, and 'Against' (Choice D) indicates opposition, which is unrelated to the prefix 'pre-.' Therefore, the answer is 'Before.'

Correct Answer: C

Rationale: The given sentence, 'If it rains tomorrow, the picnic will be canceled,' is a complex sentence. It consists of an independent clause 'the picnic will be canceled' and a dependent clause 'If it rains tomorrow.' A simple sentence contains just one independent clause, a compound sentence contains two or more independent clauses, and a compound-complex sentence contains two or more independent clauses and at least one dependent clause. Therefore, choices A, B, and D are incorrect for this sentence.

Correct Answer: C

Rationale: The main clause is the independent clause that can stand alone as a complete sentence. In this sentence, 'She finished her work on time' is the main clause because it expresses a complete thought independently. Choices A and B are subordinate clauses as they cannot stand alone as complete sentences. Choice D lacks the subject 'she,' making it incomplete and not a main clause.

Correct Answer: B

Rationale: The correct usage of 'affect' in a sentence is as a verb meaning to influence something, as in 'The weather will affect our plans.' Choice A is incorrect because 'affect' should be 'effect,' which is a noun representing the result of an action. Choice C is incorrect as 'affect' should be 'effect' to describe a disorder. Choice D is incorrect because 'affect' should be 'effect' to convey the result of the news.