问下白勇书上提到的关于where的意思

daijiajing

白勇语法大全上第四页上有道题:

Where once the union had acquiesced to the prejudices of its English-speaking members by supporting the imposition of an alien tax on immigrant workers, after 1897 the United Mine Workers made a determined effort to enlist Italians and Slavs in its ranks.

选项中第一个词有用Where和While两种。正确答案是和划线部分一样。解释说Where在这里是“尽管”的意思。但是我查了好多语法书都没查到Where有让步状语从句的这个用法。请问各位where可以解释为尽管吗？谢谢！

jtcoffeebean

白勇的解释很有道理啊，而且og更偏好where当它和while同时出现时。

我是混了AC，白勇的解释4能很好解决，C是典型的容易误解为(who are)in support of的语法错误，与逻辑意义不符