这是龙楠网友的提问：

刚在本站看到刘老师的一篇文章：https://www.cpsenglish.com/article/176

我觉得这是一个很好的问题，想提出来供大家探讨一下。

其实关于薄冰老师的观点国内有多本语法著作和用法词典提及过，而且薄冰老师自己也在多本语法著作中提及过two-months-old, four-months-old, four-months-long, five-feet-long之类的用法，除《高级英语语法》外，薄冰老师至少还在以下书中有过类似说法：

1.《英语词汇疑难用法解答》（薄冰、司树森）第3辑p233：

数词+名词+old, long, high等形容词，如：

a five-year-old child (year用单形，但a two-months-old child需用复形months)

a four-months-long winter

a three-hundred-feet-high buildingo

数间+名词，如：

a two-hours walk (也可以用 two hour’s，two-hours 或较为文气的 two-hour)

a five-year plan

2.《薄冰英语用法问答1144例》p48：

这里可用 months 与 feet 吗？

有读者问：《英语沙龙》一期中举例有a two-months-old baby 和 a three-hundred-feet-high building, 皆用复形 months 与 feet, 不知何故?

这种结构中的度量名词一般皆应用单形。但也有例外，如 a four-months-long winter, 再如 a three-feet-long stick。美国口语似乎也用 a two-months-old baby。

除薄冰老师外，王福祯也在多本书中提及过类似观点：

《新时代英语惯用法词典》（王福祯）p618：

当“一以上的基数词+表示时间的名词+old”用作定语时，名词多用单数。

a five-year-old boy一个5岁的男孩

an eighteen-month-old child一个一岁半的孩子

her three-year-old son她的3岁的儿子

偶尔也有用复数名词的情况：

a six-years’-old child 一个6岁的孩子

her six-years-old child 她的6岁的孩子

a three-months-old baby 一个3个月的婴儿

a three-days’-old newspaper 一张已出版3天的报纸

如不用 old, 而代之以其它的形容词，month 与 year 则多用复数形式：

a our-months-long winter 一个历时4个月的冬天

seven years dead 死了7年

如“基数词+year+old”结构用作名词，year仍须用单数形式：

these twenty-year-olds 这些20岁的年轻人

先撇开王福祯的书不说，薄冰老师作为国内知名的语法学家，在多本语法书提及此观点，显然不属于笔误，应该是有依据的，而且这个依据应该是原版著作中的。欢迎有兴趣的老师和网友参与讨论和提供相关原版素材。谢谢！

个人觉得，这种追本溯源的问题要弄清，其实也不难。很明显，这种用法在当代英语中被视为不规范的用法，所以要解决这个问题就只能从比较古老的语法书中去找，这样问题就有了研究方向。鉴于能问出这样问题和参与讨论的网友们都是高手，所以我就简单说说，大家一看就明白了。另外强调一点，以下内容在现在看来有些是不规范的英语用法，切记切记！

Poutsma在其1914年的著作“A Grammar of Late Modern English - Part 2 - The Parts of Speech 1, A - Nouns, Adjectives and Articles”以及1926年的著作“A grammar of late modern English Part 2, the parts of speech. 2, The verb and the particles”中都有详细介绍，如果有兴趣可以去看看！

A Grammar of Late Modern English - Part 2 - The Parts of Speech 1, A - Nouns, Adjectives and Articles（1914年）的P270-271：

a five-year-old boy

the four-months-old child

a four-months-long winter

an eighteen-months'-old child

a three-thousand-feet-high fjeld.

大家看看是不是和薄冰老师列举的例子很吻合，甚至是一模一样。只是在这本书中Poutsma对于这些现象进行了总结和举例，但是泛泛而谈。但是在1926年的著作“A grammar of late modern English Part 2, the parts of speech. 2, The verb and the particles”P563就进行了较为完整系统的论述，我们可以看看：

Observe also that seven-league boots varies with seven-leagued boots. It may be added that about the form of adnominal combinations consisting of definite numeral + name of measure (+ adjective) the language has not come to an established system. This is not the place to discuss the subject at length. Suffice it to say that, judging from the numerous examples that have come to hand,

a) in the combination consisting of definite numeral + name of measure of time the plural is rather more frequent than the singular, and is often furnished with the apostrophe. Thus a four-years (or a four years') course seems to be mostly preferred to a four-year course.

b) in the combination consisting of definite numeral + name of another measure than one of time the singular is far more frequent than the plural, which is sometimes furnished with the apostrophe. Thus a ten-mile walk is distinctly the ordinary form, not a ten-miles (or a ten-miles') walk.

c) in the combination consisting of definite numeral + name of measure of time + adjective (mostly old) the singular is preferred to the plural, so far as the noun year is concerned, other names of measure being mostly placed in the plural, which is more often than not furnished with the apostrophe. Thus a two-year old sheep (O.E.D.) is more common than a two-years (or two years') old sheep; conversely a six months (or six-months') old child is more frequent than a six-month-old child.

Names of other measures than one of time in similar combinations （feet excepted) are almost regularly kept in the singular, thus a two-mile-long footpath, but a two-thousand-feet-high mountain.

这是Poutsma从众多的例句中在当时总结的规律。

看到这里，再想想前面薄冰老师提到的那些用法，是不是对应上了！所以我很肯定薄冰老师认真拜读过Poutsma的这两本书。强烈建议龙楠网友看看这两本书关于此的描述，一定能解答你的困惑！

其他的老的著作比如Curme的，Kruisinga的和Jespersen的我也翻看了，都没有像Poutsma这么详细的介绍。

多说一句，薄冰老师这样的大咖肯定不是瞎说的，很明显这些说法都是来自于Poutsma的著作，只是时过境迁罢了！