The inquiry that long-duration, coast-observing, stratospheric airships using renewable energy systems were feasible appropriate technology investments were made. Although feasible, such airships were not without many development challenges and airship size was strongly influenced by the seasons and coastal latitudes.
Wide-area surveillance for months at a time is presently impossible as neither satellites nor aircraft can provide these capabilities simultaneously. However, renewable energy technology enough to seriously consider building aircraft for ultra-long duration flights. In this arena, airships have significant potential. Airships, unlike aircraft, generate lift from buoyancy instead of through aerodynamics. Consequently, airships do not need to stay in motion to remain aloft. Therefore, they can stay over a specific location as well as move to a new location. In addition, airships can carry large-volume, heavy payloads. characteristics make airships superb candidates for long-endurance surveillance missions.
Result:
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Correct answer: investigations
Explanation: The word 'investigations' is a noun that fits grammatically as the subject of the sentence, indicating the act of examining power management and distribution architectures. It aligns with the plural form needed to match the context of multiple studies being conducted.
Meaning: 'Investigations' refers to the systematic examination or inquiry into a subject, in this case, the technologies for renewable electrical power systems.
Wrong options:
- investigates: This is a verb form that does not fit as a subject in this context, as the sentence requires a noun.
- investigate: This is the base form of the verb and cannot function as a subject in this sentence.
- investigating: This is a gerund form that does not serve as a noun subject in this context.
Correct answer: concluded
Explanation: The verb 'concluded' fits grammatically as the past tense verb that describes the result of the inquiry. It indicates that the inquiry reached a decision or determination about the feasibility of the airships.
Meaning: 'Concluded' means to arrive at a judgment or decision after consideration, indicating that the inquiry reached a final determination.
Wrong options:
- summed: This verb implies adding up or totaling, which does not fit the context of reaching a conclusion.
- concerned: This verb suggests a state of worry or interest, which does not convey the idea of reaching a decision.
- reached: While this verb could fit, it is less precise than 'concluded' in indicating a final decision.
Correct answer: provided that
Explanation: The phrase 'provided that' introduces a conditional clause, indicating that the feasibility of the airships is contingent upon certain conditions being met, which fits logically and contextually in the sentence.
Meaning: 'Provided that' means 'on the condition that' and sets a prerequisite for the feasibility of the airships.
Wrong options:
- even if: This phrase suggests a concession rather than a condition, which does not fit the context of feasibility being dependent on technology investments.
- unless: This implies a negative condition, which does not align with the positive assertion of feasibility in the sentence.
- if only: This phrase expresses a wish or regret, which does not convey the conditional nature required in this context.
Correct answer: has progressed
Explanation: The phrase 'has progressed' is in the present perfect tense, indicating that the progress has occurred over time and is relevant to the present situation, fitting grammatically and contextually in the sentence.
Meaning: 'Has progressed' means that advancements have been made in renewable energy technology up to the present time.
Wrong options:
- progressed: This is the simple past tense, which does not convey the ongoing relevance of the progress to the current situation.
- was progressing: This past continuous form suggests an ongoing action in the past, which does not fit the context of current relevance.
- will progress: This future tense does not fit as it implies that progress is expected to happen later, rather than indicating that it has already occurred.
Correct answer: These
Explanation: The word 'These' is a demonstrative pronoun that correctly refers to the plural characteristics mentioned earlier in the sentence, fitting grammatically and contextually as it points to specific items being discussed.
Meaning: 'These' refers to multiple items that are close in context, in this case, the characteristics of airships.
Wrong options:
- The: This definite article does not fit as it does not indicate plurality or specify the characteristics being discussed.
- This: This singular demonstrative does not match the plural noun 'characteristics' in the sentence.
- That: This demonstrative suggests something further away or less relevant, which does not fit the context of directly referring to the characteristics mentioned.
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