Correct Answer: A

Rationale: The correct answer is A. In this sentence, the phrase 'who lives next door' is a non-essential element providing additional information about the teacher. It is correctly set off by commas. Choice B does not use any commas to set off the non-essential element, making the information essential to the sentence. Choice C uses an unnecessary comma before 'who,' which disrupts the flow of the sentence. Choice D incorrectly places the non-essential element at the end of the sentence without appropriate commas, making it less clear and concise.

Correct Answer: C

Rationale: Combining the sentences is most effective when using 'but' to contrast the two ideas. Option C is concise, clear, and provides the best flow, accurately capturing both the contrast 'but I lost them' and the sequence of events 'After spending hours looking for them, I found them in the freezer.' Options A, B, and D do not effectively combine the sentences or maintain the sequence of events and contrast between keeping track of the keys and losing them.

Correct Answer: A

Rationale: The correct answer is choice A, 'She said that she would finish the report yesterday.' This sentence contains a verb tense error. The reported speech 'She said' requires the verb 'would' to maintain the past tense. Choices B and D are correct as they use the appropriate verb tenses 'went' and 'will play.' Choice C is also correct as it uses 'was released' to match the past perfect tense 'had seen.'

Correct Answer: C

Rationale: Relative pronouns are acceptable in a research paper for connecting clauses. Colloquialisms (choice A) are informal expressions that are not suitable for academic writing. Contractions (choice B) are considered too casual for a research paper. The second-person point of view (choice D) should be avoided in research papers as it can make the writing less objective and scholarly.

Correct Answer: D

Rationale: The suffix '-ize' is used to form verbs by converting nouns or adjectives into verbs. For example, 'real' can become 'realize' or 'modern' can become 'modernize.' On the other hand, the suffixes '-ation,' '-ness,' and '-ity' are commonly used to form nouns. '-ation' is often used to form nouns from verbs (e.g., 'celebrate' to 'celebration'), '-ness' is used to form abstract nouns from adjectives (e.g., 'kind' to 'kindness'), and '-ity' is used to form abstract nouns from adjectives (e.g., 'happy' to 'happiness'). Therefore, the correct answer is 'D' because '-ize' is not commonly used to form a noun from some other part of speech.