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Difficulty: MediumPlural and Possessive Nouns and Pronouns

The passage below contains a blank. Based on the grammatical context of the passage, what form of the noun 'star' correctly completes the blank?

Answer:In 1912, astronomer Henrietta Swan Leavitt analyzed photographic plates of the Magellanic Clouds to study variable stars. While observing these celestial bodies, she noted a pattern linking the time it took for each one to complete a cycle of brightness to its actual light output. Ultimately, Leavitt's discovery of the relationship between these 【stars'】 luminosity and pulsation period revolutionized modern astrophysics by allowing researchers to measure cosmic distances for the first time.

Answer

stars'
The correct answer is the plural possessive noun 'stars''. The plural demonstrative pronoun 'these' indicates that the noun must be plural, and the noun 'luminosity' immediately follows the blank, indicating that the stars possess the luminosity. Therefore, the plural possessive form 'stars'' is required.

Step-by-Step Solution

1
Analyze the grammatical context preceding the blank to determine number.
The demonstrative pronoun 'these' precedes the blank, which indicates that the following noun must be plural ('stars').
Demonstrative pronouns must agree in number with the nouns they modify.
2
Analyze the grammatical relationship between the blank and the subsequent noun.
The noun following the blank is 'luminosity'. Since the luminosity belongs to the stars, the plural noun 'stars' must be in the possessive case ('stars'').
A noun modifying another noun to show ownership or association requires possessive punctuation.

Key Concept

Plural and Possessive Nouns
Estimated Time:1m 0s
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Topics

Plural and Possessive Nouns and Pronouns

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