“Whoissinginginthehall?” “________isMr．Smith．________isknowntousth

“Who is singing in the hall?” “________ is Mr．Smith．________ is known to us that it is he who wrote it．A.It … itB.It … AsC.She … ItD.She … As

A解析前一个的it作“这，那”解，指上下文所指的人或事，而后一个的it，是用作形式主语结构，指代后面的that it is he who wrote it．这句句子的意思是“谁在大厅里唱歌?”“是史密斯先生，众所周知，是他谱写了那首曲子。”

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