Correct Answer: D

Rationale: The correct plural form of the noun 'class' is 'classes.' When forming the plural of 'class,' you add 'es' to the singular form. Choices A, B, and C do not correctly represent the plural form of 'class' and are therefore incorrect. Choice A is the singular form, choice B is incorrect as it includes an apostrophe, and choice C shows possession which is not required for pluralization.

Correct Answer: C

Rationale: The correct plural of 'century' is 'centuries'. In English, to form the plural of most nouns ending in -y, you change the -y to -ies. Choice A, 'Centurys', is incorrect because it does not follow this rule. Choice B, 'Centures', is also incorrect as it does not provide the correct plural form. Choice D, 'Centuryies', is a completely incorrect and non-standard plural form of 'century'. Therefore, the correct answer is 'Centuries'.

Correct Answer: D

Rationale: In this sentence, 'bass' refers to a guitar with four strings that makes low sounds. The context of Natalie practicing suggests that it is referring to a musical instrument, specifically the bass guitar, rather than a fish, sound, or voice. Therefore, the correct answer is D. Choice A, 'Kind of fish,' is incorrect as the sentence context does not relate to fish. Choice B, 'Low and deep sound,' is incorrect because the sentence refers to practicing an instrument, not just a sound. Choice C, 'Lowest male singing voice,' is also incorrect as the sentence context is not related to singing but to playing an instrument.

Correct Answer: D

Rationale: The correct answer is D (Henry) because the adjectives 'strong and healthy' describe 'Henry.' In this sentence, 'Henry' is the subject being described as strong and healthy, not 'weeks,' 'his,' or 'surgery.' While 'weeks' and 'surgery' are nouns mentioned in the sentence, they are not the nouns being described by the adjectives in question. 'His' is a possessive pronoun referring to Henry and does not match the criteria of being directly described by the adjectives 'strong and healthy.' Therefore, 'Henry' is the noun that the adjectives specifically describe in this context.

Correct Answer: B

Rationale: The correct answer is writing a postcard (Choice B). A postcard is a casual form of communication, typically sent to friends or family, making it a suitable context for informal language. Using informal language in a seminar (Choice A) would be inappropriate as it is a formal setting where professional language is expected. Talking to your boss (Choice C) and participating in a professional conference (Choice D) also require formal language to maintain professionalism and respect for the workplace environment.