题目解析:
B 整段大量篇幅在讨论 building material,建议用排除法。A 的 new building material 定位到第四句,但是 A 选项的 hard to find 明显和这句话矛盾,错误;同样 B 选项也定位到这一句,no long limits 和这句话吻合,正确,选 B: Today technology has progressed to the point where it is possible to invent new building materials to suit the type of structure desired. C 的三种材料定位到第三句的列举部分,但很明显,他们应该是以前的主要建筑材料,不是现在。In earlier times it was necessary to design structural systems suitable for the materials that were available, such as wood, stone, brick. D 没说选项在原文没有提及,看上去长得像倒数第二句,但意思不同。