Correct Answer: B

Rationale: In the sentence 'One out of four doctors,' the subject is 'One,' which is singular. Therefore, the verb that follows should also be singular. The correct verb form in this case is 'subscribes,' not 'subscribe' or any other form. This subject-verb agreement rule ensures that the sentence is grammatically correct. Choice A 'subscribe' is incorrect as it is in the plural form and does not agree with the singular subject. Choice C 'subscribing' is in the gerund form and does not function as the main verb of the sentence. Choice D 'are subscribed' is in the passive voice and does not match the active voice required in this sentence.

Correct Answer: D

Rationale: The word 'their' is used incorrectly in the sentence. The correct word should be 'they're,' which is a contraction for 'they are.' The sentence should say: The boys leapt up, happy to assist their favorite teacher. Choice A, 'leapt,' is correctly used as the past tense of 'leap.' Choice B, 'happy,' is also correctly used as an adjective to describe the boys' emotional state. Choice C, 'assist,' is appropriately used as a verb to show the boys' willingness to help.

Correct Answer: A

Rationale: The word 'stealthy' is used incorrectly in the sentence. The correct adverb form of the word should be 'stealthily' to modify the verb 'moving.' Therefore, it should be 'Moving stealthily, the sneaky little boy reached for the cookie jar on the topmost shelf.' Choices B, C, and D are all used appropriately in the sentence. 'Sneaky' describes the boy, 'reached' is the action verb, and 'topmost' correctly describes the location of the cookie jar.

Correct Answer: C

Rationale: The phrase 'had rarely' is not used correctly in the sentence. The correct form should be 'rarely eaten' instead of 'had rarely' to convey the past tense of the children's eating habits before their hospitalization. 'Had rarely' is incorrect because it does not match the structure needed to describe the children's eating habits in the past. Choices A, B, and D are grammatically sound and fit appropriately in the sentence.

Correct Answer: C

Rationale: The correct answer is C. The sentence requires an infinitive form of the verb 'to conduct' after the verb 'promised.' This structure is commonly used in English grammar, where the main verb 'promised' is followed by an infinitive verb form. Therefore, the sentence should read: 'The students promised to conduct themselves with quiet dignity.' Choice A ('conduct') is incorrect as it is not in the infinitive form required after 'promised.' Choice B ('conducting') is incorrect as a gerund does not fit the grammatical structure of the sentence. Choice D ('to be conducted') is incorrect as it changes the meaning of the sentence, suggesting that someone else will conduct the students, rather than the students conducting themselves.