問題詳情

第 18 題至第 21 題為篇章結構，請依文意，從四個選項中選出最合適者，各題答案內容不重複。       A new study finds that the concave-eared torrent frog that uses ultrasonic communication can tune its ears like a radio dial to block out lower pitched background noise. 18 This is contrary to everything that we knew about the frog’s auditory system.      Earlier this year, the researchers reported that male torrent frogs can localize sound with unusual accuracy to find females during ultrasonic mating duets. 19 This surprised the team, because in all other frogs eardrums always respond the same way to a sound stimulus.      Further examination revealed that the frogs were actively opening and closing their eustachian tubes, two narrow channels that connect the mouth cavity to the left and right ear. 20 In practice, shifting to high-frequency hearing could help the frogs pick out mating calls during a storm, when the low-pitched noises of plunking raindrops, booming thunder, and rushing water dominate. 21
18
(A) This makes the frog the only known animal that can physically control which frequencies it hears by opening and closing parts of its ears.
(B) Further studies of the amphibian’s hearing showed that its eardrums vibrate in response to ultrasonic noises, but only some of the time.
(C) By contrast, the frogs have evolved the biological equivalent of earmuffs to block out all sounds of a certain frequency range.
(D) There is no doubt that the frogs’ hearing ability is still crucial to their survival.

參考答案

答案：A
難度：適中0.464286
統計：A(13),B(6),C(5),D(2),E(0)

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