核心问题
20 miles is a long way. 为什么在复数主语后用单数动词？
词典解答
名词短语20 miles在概念上被看成一个表示距离的单位，故其谓语动词通常用单数，也
就是说,这里采用的是概念一致的原则:
Two miles is as far as they can walk. (That distance is...) (CGEL) 他们能走两英里。请做下面的英语试题：
A thousand miles no longer ____ much to us today, for modern jets can easily get us over this distance without a matter of a few hours.
A. meant B. mean C. means D. will mean
[附注]当强调距离的各个组成部分时,亦可使用复数动词(见 minutes):
Many miles were covered by him on his bicycle. 他骑自行车骑了很远的路程。