This sentence uses the adjective “breathless” to modify the verb “watched”. An adjective cannot be used to modify a verb, but an adverb can, so an adverb would be more appropriate. The corrected sentence reads, "The audience watched breathlessly as the contortionist brought her leg behind her back and in front of her nose."

In this sentence, the adjective “tragic” is misused to modify a verb, “cut short.” An adverb would be correct here. The corrected sentence reads, "The mademoiselle’s promising career in opera was tragically cut short by a falling piano."

In this sentence, the adjective “smooth” is used to modify the verb “went.” An adverb would be correct in this situation. The corrected sentence reads, "Francisca was nervous that the sudden arrival of fifty international students would be overly chaotic, but fortunately everything went smoothly."

Adverbs often end in "–ly" (e.g. "quickly," "slyly," and "happily"). Without this "–ly" ending, swift is only an adjective (e.g. "He is a swift runner."). In this case, “swift” acts as an adverb (describing how the track star runs), so it should be written “swiftly.”

This sentence uses an adverb (effortlessly) to describe a noun (trick). An adjective would be more appropriate. The corrected sentence reads: While the trick may look effortless, the actual execution of a perfect double back handspring is quite tricky to achieve successfully.

This sentence uses the adjective "terrible" to modify the verb "performed." An adverb is more appropriate. The corrected sentence reads, "Although the eighth grade math bowl team did excellently in practice, the members performed terribly in the actual tournament."

This sentence uses a comparative (“more”) to compare more than two things—sixteen, in fact. For a comparison involving more than two things, a superlative (“most”) is used. The corrected sentence reads, "Of the sixteen jellybean varieties available, the turquoise tasted most exquisite."

This sentence uses the comparative adjective “more” to compare four things. The superlative “most” would be correct here, as the superlative form of adjectives is used when three or more things are being compared. The corrected sentence reads, "Of her four classes that semester, Introduction to Biology was the most challenging."

The error in this sentence is "less" because "health problems" are countable nouns—you can count the number of health problems a person has. When referring to countable nouns, you should use "fewer" instead of "less." The beginning of this sentence, then, should read, "People who experience fewer health problems."

When describing physical distance, the adjective "farther" should be used. However, when describing figurative distance, the adjective "further" should be used. Given that the distance of a house from another house is being described—that is, a physical distance—the adjective "farther" should be used, not "further."