問題詳情

＜B＞ Rain forms when small drops of water come together inside a cloud to form icecrystals, __21__ fall out of the cloud when being large enough, and hit the ground as eitherrain __22__ snow. A scientist named Vincent J. Schaeffer thought these ice crystals couldbecome “seeds” for forming larger crystals, and they would “grow” as they fell through thecloud. When Schaeffer dropped crystals of dry ice into the cloud __23__ airplane, hesucceeded in producing a little snow.Later, another scientist, Bernard Vonnegut, found that silver dioxide crystals couldalso work __24__ seeds. The molecular structure of silver iodide is very similar to __25__of ice. But silver iodide will not melt as fast as ice. This is a better way to seed clouds.
21.
(A) they
(B) that
(C) which
(D) and

參考答案

答案：[無官方正解]
難度：適中0.5
統計：A(0),B(0),C(0),D(0),E(0)

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