单选题 While attempting to look into the case,______
A. he found it was difficult B. the case was difficult
C. it happened that the case is difficult D. difficult as the case

【正确答案】 A
【答案解析】[解析] 句子大意为：当准备着手调查该案件的时候，他发现这个案件很棘手。本题考 查语态一致和语义连贯。题干中的分句省略了动作的施动者，所以，主句中应该有表示施动 者的人称代词做主语。所以，正确答案是A。