This question tests the use of infinitives to express purpose. The phrase 'to keep the temperature steady' acts as an infinitive of purpose, explaining why the students check the thermometer, fitting the procedural context after the semicolon. Choice A, 'to keep,' correctly introduces this purpose clause. Choice B's 'keeping' creates a participial phrase that dangles without clear attachment, Choice C's 'kept' introduces a past participle that disrupts the present tense sequence, and Choice D's 'keep' is a bare infinitive that lacks the 'to' needed for purpose. In procedural writing, infinitives of purpose are useful for clearly stating the reason for an action without ambiguity.

This question tests pronoun-antecedent agreement. The pronoun must refer back to 'notebooks,' which is plural, requiring a plural object pronoun to describe their storage. Choice B, 'them,' correctly matches in number and serves as the object of 'stores.' Choice A uses the singular 'it,' which fails to agree with the plural antecedent, Choice C introduces an irrelevant masculine pronoun 'him,' and Choice D's 'this' is a demonstrative that does not function as a personal pronoun here. When selecting pronouns, always trace back to the antecedent to ensure agreement in number, gender, and person.

This question tests pronoun case and reference, requiring an objective pronoun to serve as the object of 'address.' The antecedent is the plural 'questions' implied from 'ask questions,' so 'them' correctly refers to these questions as the things the speaker will address. Choice A 'they' is nominative and cannot function as an object; C 'their' is possessive, which would incorrectly suggest ownership; and D 'theirs' is a possessive pronoun that doesn't fit the object role. In pronoun questions, always determine the grammatical role—such as subject or object—and match the case accordingly while ensuring clear reference to the antecedent.

This question tests verb tense, specifically the use of past perfect to indicate an action completed before another past event. The timeline markers 'last spring' and 'by the time the final report was submitted in June' establish past actions, with the identification happening prior to the submission, so 'had identified' correctly uses past perfect to show this sequence. Choice A 'identifies' is present tense, mismatched with the past context; B 'identified' is simple past, which doesn't convey the prior completion; and D 'will identify' incorrectly shifts to future. In tense questions involving timelines, identify the order of events to choose the form that accurately reflects sequence, such as past perfect for earlier actions in past narratives.

This question tests pronoun-antecedent agreement and case, ensuring the pronoun matches its referent in number and functions correctly in the sentence. The pronoun in the blank serves as the subject of 'is recorded,' requiring a nominative singular form to parallel the singular 'every fossil,' which is treated distributively as singular; 'it' correctly refers back to each individual fossil or its tag being recorded. Choice A 'they' is plural and would require a plural verb like 'are' for agreement, but the verb 'is' is singular; B 'them' is an objective pronoun that cannot act as a subject, and D 'their' is possessive, unfit for the subject role. When evaluating pronouns, check both the number agreement with the antecedent and the pronoun's case based on its grammatical function in the clause.

This question tests the use of participial phrases to modify nouns and provide descriptive detail. The blank introduces a phrase modifying 'the comet’s tail,' describing the condition under which it appeared; 'Viewed' is a past participle that correctly forms a passive participial phrase implying the tail was observed through the filter. Choice A 'To view' creates an infinitive phrase that doesn't logically modify the subject; C 'Viewing' is a present participle suggesting active viewing by the tail itself, which is illogical; and D 'When viewing' introduces a subordinate clause that disrupts the sentence structure. When dealing with introductory phrases, ensure they logically modify the following subject to avoid dangling modifiers.

This question tests subject-verb agreement with collective nouns and present tense for habitual actions. The subject 'series' is singular, and the phrase 'including one segment about the old harbor' is a nonrestrictive modifier that doesn't alter the number, so 'is' correctly matches in the present tense to describe the ongoing broadcast schedule. Choice A 'are' is plural, mismatching the singular subject; B 'were' shifts to past tense unnecessarily; and D 'have been' introduces present perfect, which isn't needed for the habitual present context. For collective nouns like 'series' or 'committee,' treat them as singular unless the context emphasizes individual members acting separately.

This question tests pronoun-antecedent agreement, focusing on number consistency. The antecedent 'each tree' is singular and distributive, requiring a singular pronoun 'it' to refer back to each individual tree not being damaged. Choice A 'they' and C 'them' are plural, mismatching the singular 'each'; D 'we' introduces an unrelated first-person pronoun that doesn't refer to the trees. When 'each' is used, it emphasizes individuality, so always pair it with singular pronouns and verbs to maintain agreement.

This question tests subject-verb agreement with collective nouns and the use of present progressive tense. 'Committee' is a singular collective noun, so 'is' correctly agrees with it, and 'is planning' uses present progressive to indicate a future intention from a present perspective. Choice A 'are' treats the committee as plural, which is inconsistent here; C 'were' shifts to past; and D 'be' is subjunctive or infinitive, not fitting the indicative mood. Collective nouns like 'committee' or 'team' typically take singular verbs in American English unless emphasizing internal division.

This question tests verb tense consistency in a past narrative sequence. The actions 'placed,' 'wrote,' and 'was poured' are in simple past, so 'increased' maintains consistency to describe the subsequent change in mass. Choice A 'increases' shifts to present tense, breaking the past sequence; C 'has increased' uses present perfect, unsuitable for a completed past event; and D 'will increase' incorrectly introduces future tense. In passages with established timelines, match the tense of surrounding verbs to ensure logical consistency unless a shift is clearly signaled.