dozen、hundred、score用法上的异同?rt,请讲得详细一点哟

1.当词与数字连用时,通常不加复数词尾-s,也不后接介词 of.如：
I want three score eggs.我要60只鸡蛋.
He is a man of three score years.他六十岁.
Two hundred (thousand) students went there.有两百(千)学生去了那儿.
注：有人 score,dozen 之后有时也接 of,但惯用法省略 of 则常见.
当 million 用作中心词(即其后不接名词或数词)时,有时也可带复数词尾-s.如：
The population of New Zealand is now three million(s).新西兰现有人口三百万.
2.当词不与数字连用,而是表示不的泛指数时,则要加复数词尾-s,而且要后接介词 of,然后才能接名词.如：
I’ve read it dozens (scores) of times.我读过它几十次.
Thousands of students entered the contest.数千名学生参加了这次比赛.
Millions of people died in the war.有数百万人次战争中丧生.
注：若不名词,则不用介词 of.如：
Millions (of people) are homeless.千千万万的人无家可归.
3.当词与 a few,several,many 等数目不很的词连用时,带不带复数词尾 -s 均可,注意：若不带复数词 -s,其后的介词 of 可以省略；若带复数词尾-s,则其后介词 of 省略.如：
在那儿我见到了数百外宾.
正：There I saw several hundred(s) of foreign guests.
正：There I saw several hundred foreign guests.
注意 some hundred persons 与 some hundreds of persons 含义不同：前者指“大约一百人”,some＝about a；后者指“几百人”.
4.当词后面的名词有了 the,these,those等特指限定词修饰时,或其后的接的是 us,them 的人称代词时,则此时用介词 of.如：
two dozen of them 它们中的两打
three scores of these eggs 鸡蛋中的三打
five hundred of the workers 工人中的五百人
5.注意与介词 by 连用的例子：
The eggs are sold by the dozen.鸡蛋按打出售.
The ants arrived at the picnic by the hundred(s).成群的蚂蚁来到野餐的地方.
They were sold by the thousand(s).它们被大批大批地(论千地)出售.
Pack them in dozens.把它们成打地包起来(即每12个一包).