The peaks of a mountain range, acting like rocks in a streambed, produce ripples in the air flowing over them; the resulting flow pattern, with crests and troughs that remain stationary although the air that forms them is moving rapidly, are known as "standing waves".
95.The peaks of a mountain range, acting like rocks in a streambed, produce ripples in the air flowing over them; the resulting flow pattern, with crests and troughs that remain stationary although the airthat 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
答案:C 我选的E
解释是: The use of the active voice in the verbs of the subordinate clauses provides greater clarity of meaning. 但我认为E更简洁,求指教~