看樣子時代真的變了。我特別找 GMAT 當例子，因為它考的是最正式的文法以及最嚴謹的用法和文體。很多（日常性質的）“standard English” 可以的用法/文法放在 GMAT 裡不會是答案。但是隨著時代變遷，以前不可以的現在卻是可以（特別是新的 GMAT Focus Edition 去掉了 sentence correction 考題，會遇到 None of … 選 is/are 的考題機率更低）。
這兩本 GMAT 是同一個作者，基本上是兩個不同版本，一個是 2003 年出版，另一個是 2012 年出版。一樣的例句，文法解說 "none"的部份改了。2003年舊版的是要接單數動詞，2012年版本的則是接單數或是複數動詞都有可能，依內文而定。
Crash Course for the GMAT, 2nd ed, by Cathryn Still, Princeton Review, 2003
p24:
Another note on subject/verb agreement: Words such as none, no one and every are singular, and should be followed by a singular verb.
Examples:
…
None of the executives hired last year is still employed here.
Crash Course for the New GMAT, 3rd ed, by Cathryn Still, Princeton Review, 2012
p40:
Another note on subject/verb agreement: The Words no one and every are singular, and should be followed by a singular verb. The word none is trickier; it can be singular or plural depending on the context .
Examples:
…
None of the executives hired last year is still employed here.
同場加映：
The American Heritage® Dictionary of the English Language
