最近，我的一個VIP學生上課說到，從來不知道and, so之類的連詞怎麼用標點，希望我給他講一下。這個問題貌似中國老師都不教的，我也是有幸被外教指出therefore的標點用法後才有這個意識，然後自己也去看了一些相關的書，才算梳理清楚了，今天給大家分享一下～
William Strunk 的 The Elements of Style 書中有專門針對標點的介紹。整本書短小精悍，全書都是乾貨～我至今都沒有看完😄。這邊單獨把標點部分的內容羅列出來，一起來了解一下。
Red, white, and blue
Gold, silver, or copper
特殊：商號的名稱中，最後一個逗號通常省略，如，Brown, Shipley and Co.
The best way to see a country, unless you are pressed for time, is to travel on foot.
The early records of the city have disappeared, and the story of its first years can no longer be reconstructed.
The situation is perilous, but there is still one chance of escape.
I have heard his arguments, but am still unconvinced.
He has had several years』 experience and is thoroughly competent.
Stevenson’s romances are entertaining; they are full of exciting adventures. （推薦）
Stevenson’s romances are entertaining. They are full of exciting adventures.
Stevenson’s romances are entertaining, for they are full of exciting adventures.
為什麼推薦第一個例句中用分號連接2個簡單句的方法呢？英文是追求簡潔的語言。兩個句子之間有緊密的邏輯關係，如果用句號隔開，連接關係不夠緊密；那麼連詞連接的話也較標點複雜一點。
如果置於第二個分句前的不是連接詞，而是副詞，如accordingly, besides, then, therefore, thus, 則仍需用分號與第一個從句分開。
I had never been in the place before; besides, it was dark as a tomb.
這個很好理解，因為副詞是可以修飾整句話的。besides在這裡就是修飾後面整句話。就像我們說，Clearly, he is lying. 是一樣的道理。
如果不用分號，可以這樣：
I had never been in the place before, and besides, it was dark as a tomb.
但如果在簡單句中，可以加或不加逗號
Therefore, prices have risen with the demand. (CCTV見聞）
Therefore the situation will only grow worse. (現代大學英語精讀第三冊）
如果共用一個主句，後面可以不用逗號
He has injured, therefore unable to play.
最後的最後，我們來看一下這段話👇
After graduating from Barnard College in Manhattan in 1942, Highsmith found freelance work scripting comic books—one of few women in the industry at the time. This funded her life in New York for years and seems to have influenced her fiction, which is full of secret identities, alter egos, hot pursuits and daring escapes. But this work embarrassed her, and she scrubbed all traces of it from her archives. （經濟學人）
在英文的表達習慣中，but, and, so是可以放句首的，並且一般不加逗號。所以，同學們如果想鞏固或者拓展標點的用法，還是要多看原汁原味的文章。
好了，來做個總結。
1. 簡單句，連詞 + 簡單句；
2. 詞，詞，連詞 + 詞；
3. 短語，短語，連詞 + 短語；
4. 連詞 + 句子；
5. 副詞，句子；
6. 簡單句；副詞，句子。/ 簡單句；副詞 + ju zi ；
7. 簡單句，and therefore / therefore的替換詞 + 句子；（therefore等詞後可以加逗號）。
下期見，歡迎投稿～