xdf P115-7

when drive-ins were at the height of their popularity in the late 1950's, some 4,000 existed in the US, but today there are less than one-quarter that many.

C.there are fewer than one-quarter of that amount

E. it is less than one-quarter of that amount

答案： C

amount 不是单数吗？  我觉得C 应该说there is 吧？

E 为什么错？

这里的some 4,000 existed in the US是插入语，去掉后看，there are后面的应该是drive-ins，所以用复数

而且修饰drive-ins不能用amount呀，要用number