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。