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The peaks of a mountain range, acting like rocks in a streambed, produce ripples in the air ?owing over them; the resulting ?ow pattern, with crests and troughs that remain stationary although the air that forms them is moving rapidly, are known as “standing waves.” A) crests and troughs that remain stationary although the air that forms them is moving rapidly, are B) crests and troughs that remain stationary although they are formed by rapidly moving air, are C) crests and troughs that remain stationary although the air that forms them is moving rapidly, is D) stationary crests and troughs although the air that forms them is moving rapidly, are E) stationary crests and troughs although they are formed by rapidly moving air, is
此题如何在C和E中选。我觉得E也不错呀,比C简洁。答案是C。 |
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