专四真题单选及答案详解

41. Acute hearing helps most animals sense the approach of thunderstorms long before people___.   

41. Acute hearing helps most animals sense the approach of thunderstorms long before people___. A. do B. hear C. do them D. hearing it A 答案：【参考译文】敏锐的听觉使多数动物能远在人之前感觉到雷雨的来临。 “Acute 【试题分析】本题为语法题，考句子成份的省略与替代。【详细解答】 hearing helps”before 是主句和引导的从句具备相同的主语和谓语，从句中省略了该相 do“sense the approach of thunderstorms” 同部分，用助动词替代了与主句重复的信息． A 故答案为选项。 42. This is an illness that can result in total blindness ___ left untreated. A. after B. if C. since D. unless B 答案：【参考译文】这种病假如不加以治疗，患者会完全失明。【试题 aftersince 分析】本题为语法题，考查连词的使用方法。【详细解答】和都是引导 since“”if“”unless“” 时间状语从句，还可作因为讲，引导原因状语从句。假如和除非 if+ 都能够引导条件状语从句。但后接过去分词短语，省略的成份为主语系动词，该 B 主语只有与主句的主语相同才可省略。依照句意和句子结构，选项为正确答案。 43. The central provinces have floods in some years, and ___.