这个题目出错了!
因为dozen 和score 的用法完全类似.A和B都可以!而且,A和B的这种用法都不常见.更常见的用法是不带of.就像我们说two hundred dollars而不（常）说two hundred of dollars一样.
如,这里有“two score of”
MORE THAN TWO SCORE OF WIVES
Record of a Chicago Mao Wfyo Is arrested on a Bigamy Charge.
CHICAGO,Oct.24.— Forty two wives scattered throughout the world,four of whom
are in Chicago,was the confession made to-day by Waller I.Farnsworth.
又如,这里有"two dozen of "
More Than Two Dozen Of The Country's Most Prominent Interior Designers Descend On
Long Island's Ronald McDonald House To Unveil Unique Project.
NEW YORK,Oct.6,2013.-- 26 of the country's top interior designers create first permanent designer show house for the Ronald McDonald House of Long Island (RMH-LI),a home-away-from-home for families of seriously ill children.