| 37. Among the most complex crystals are that of silicon dioxide, which has seven different structures at various temperatures and pressures, the most common being quartz.
答案：B 分析：改为those，指代crystals.后面的which指代silicon dioxide,所以用单数has 翻译：在最复杂晶体中有二氧化硅的结晶体，二氧化硅在不同温度和压强下有7种不通结构,最常见的是石英。 39. By 1810 the 23 towns of Hampshire County, Massachusetts, had reached a remarkable uniform of economic development as well as population density. 答案： C uniform>> unification 分析：C。 D没有错误。这边表示递进也是可以的。C才是大错。同意是C，uniform常用还是制服的意思，应该改成unification。 翻译：到1810时，H国的23个镇已经达到了显著的经济发展和人口密度的统一。 | 
