XDF蓝皮书 练习一 3 （大全上没找到~）

胖嘟嘟

Although the Supreme Court ruled as long age as 1880 that Blacks could not be excluded outright from jury service,nearly a century of case-by-case adjudication has been necessary to develop and enforce the principle that all juries must be drawn from "a fair cross section of the community"
答案选A 可是为什么用“has been "呢？？？？？我选了D与划线部分只有唯一的区别也就是不用“has been"而是用is

同济的卡卡

nearly a century of case-by-case adjudication

cat19bear

同上 ：）

这道题目google 过的 老外也是这么说的
present perfect