Pair的复数二不二？

这两天看书，瞧见了这样的句子：

There was a blue compression sack that held the clothes I wasn't already wearing--a pair of fleece pants, ..., two pair of wool socks and two pair of underwear...

There was the fresh T-shirt I didn't need now that I had my Bob Marley shirt, two brand-new pair of wool socks, and a copy of Margaret Drabble's A Summer Bird-Cage.

我从来都以为pair的复数形式只有pairs，难道可以不加s？一查词典...

为什么我压根没听说过这种用法？我自认为语法基础很好啊！！！同一本书里，先来一个dare，再来一个pair。一个礼拜之内两次颠覆我深信不疑的用法，而且是这么简单、这么大众的单词，简直让我怀疑人生！

不！信！邪！

挖啊挖，终于挖出了一些可以给自己开脱的理由。

Oxford Learner's Dictionary says:

In informal North American English some people use pair as a plural form: three pair of shoes. This is not considered correct in written English.

Dictionary.com says:

When used without a modifier, pairs is the only possible plural: Pairs of skaters glided over the ice. When modified by a number, pairs is the more common form, especially referring to persons: Six pairs of masked dancers led the procession. The unmarked plural pair is used mainly in reference to inanimate objects or non-humans: He has three pair (or pairs) of loafers.

基本全中！书的作者是美国人，用的当然是北美那边的英语；不加具体数字的时候，都是pairs of...而不是pair of...，加了具体数字且没有s的复数pair形容的都是袜子不是人。不过，既然我是在书里看到的复数pair，说明至少在美国，这种用法被认为是正确的written English。

综合各种情况，最保险的选择是：把pair当成普通名词使用，复数统统加s。

那你说，美国人整那么多花样干吗？作！

P.S. 虽然我建议pair的复数始终用pairs，但以后各位至少要知道，pair不是错误。记住这一点，这篇推送也就没有白费功夫，不然就62了。（62是我家乡的方言，好奇的童鞋可以自行百度，我不解释。:P）