Oxford comma (牛津逗号)

牛津逗号（Oxford comma），又称连续逗号（Serial comma），是指如果并列三个或更多的名词，在倒数第二个名词之后添加逗号。例如
France, Italy, and Spain
假如省略这个逗号，就写成
France, Italy and Spain
两种写法都不错，但牛津逗号现在越来越流行，尤其是在美国。《牛津书写风格手册》曾建议使用，因此得名。

为什么牛津逗号值得推荐？因为英语里有同位语短语或词组，它与前面的名词也是用逗号与它隔开。同位语词组由两部分组成，中间用一个逗号。有三个或更多的名词时使用牛津逗号有助于将它与同位语词组区分开来。例如
（1）We invited the rhinoceri, Washington, and Lincoln.（“我们邀请了犀牛、华盛顿和林肯。”）
如果不用牛津逗号
（2）We invited the rhinoceri, Washington and Lincoln.（“我们邀请了犀牛，即华盛顿和林肯”，或“我们邀请了犀牛、华盛顿和林肯。”）
语句（2）有两种解读，如果读者习惯了牛津逗号的书写并且以为作者在他的写作中也遵守这个规则，读者就会理解为“我们邀请了犀牛，即华盛顿和林肯”，就是说将Washington and Lincoln（“华盛顿和林肯”）看作是复数的rhinoceri（“犀牛”）的同位词组而对它具体列举说明（好比I have two sons, John and Jack中的John and Jack）。这种理解并非完全无理，因为有可能犀牛饲养员或动物园的确有两只犀牛，还给它们分别取名为“华盛顿”和“林肯”。

但牛津逗号并不解决所有问题，例如
They went to Oregon with Betty, a maid, and a cook.
无论如何这句话都有两种理解：
“他们和贝蒂、一个女佣和一个厨师一起去了俄勒冈州。”
“他们和贝蒂（一个女佣）和一个厨师一起去了俄勒冈州。”
为避免这种语义模糊性，语句必须改写。一个好的作者或作家必须随时提醒自己，写出的语句是否会被误解。当然，故意造成歧义而产生一种特殊的修辞效果则另当别论。

Shall or will?

When I learned English thirty plus years ago in China, we were taught to say "I shall", "we shall", and "you will", "he/she/it will". That is, "shall" for the first-person verb and "will" for the second- and third-person. But coming to the US, I realize "shall" is rarely said. It is said if the speaker intends to emphasize his (her) point and in that case it's not limited to the first person. I just came across the renowned English language linguist David Crystal's The Cambridge Encyclopedia of the English Language where (on p.224) he says "[m]odern usage does not observe this distinction. Indeed, it may never have existed in the language, but only in the minds of grammarians anxious to impose order on a 'messy' area of usage". Wasn't that enlightening, especially the latter statement! I don't know if the English textbooks in China still recommend that usage. It misled a generation of English learners back then. One coworker of mine who came to the US from southern China in the 1970s still says "I / we shall" today, though this is a fellow that couldn't care less about English, judging by his frequent spelling errors and strong accent in spite of his 40+ years living in the US. Fortunately, no other rules made up by the prescriptive grammarians came into the textbooks we were using, such as the no split infinitive rule (i.e. avoid saying "to fully understand"). Apparently the English educators in China did keep an eye on the actual usage of the language in English-speaking countries.