做题思路：划线内外的句意较好理解。比较选项时，最早发现CDE中the Incan highway前有逗号，与之前内容有隔开，需要稍让人琢磨这条路与the greatest road system 之间的关系。故除剩CDE,剩AB。A中一致关系不好，B中extended可以和was在句意上保持一致，所以选B。 在答疑录音中，老英说extended是动词，而之前是一个时间短语，所以构不成并列关系，所以你很早就排除了B，你最后剩下的DE，但是我认为extended和再前面的was保持一致也讲得通；老管剩BE比，他认为B中extended不该为主动，故在这点上E比B好。可是E中extending难道不是表示一种主动状态吗？ 疑惑哪点考虑得不合理了，望老师解答。谢谢！ 相关考题（ID 167）： The greatest road system built in the Americas prior to the arrival of Christopher （Columbus was the Incan highway, which, over 2,500 miles long and extending） from northern Ecuador through Peru to Southern Chile. A.Columbus was the Incan highway, which, over 2,500 miles long and extending B.Columbus was the Incan highway, over 2,500 miles in length, and extended C.Columbus, the Incan highway, which was over 2,500 miles in length and extended D.Columbus, the Incan highway, being over 2,500 miles in length, was extended E.Columbus, the Incan highway was over 2,500 miles long, extending