ELISA ENGLISH's Blog 英語園地

K.  Use a comma after a prepositional phrase at the beginning of a sentence.

(a)  Per our conversation this morning, I will consider that the requirements are final and proceed with requesting sign offs from the business partners.

(b) To me, it can’t get any better than this.

L.  Use a comma after an adverbial dependent clause when the dependent clause precedes the main clause.  A comma is usually not required (unless for cases with extreme contrast) if the dependent clause does not begin the sentence. 

(a) After I had my dinner and before I go to bed, I usually take a shower.

(b) I usually take a shower after I had my dinner and before I go to bed.  (no comma is required)

(c) While I was eating, the door bell rang.

(d) The door bell rang while I was eating.

(e) Mary still refused to talk to him, even though he had made several apologies.  (case with extreme contrast)

M.  Use a comma to set off parenthetical elements such as appositives.  When both a city's name and that city's state or country's name are mentioned together, the state or country's name is treated as a parenthetical element. 

用逗點隔開插入語, 例如同位語, 或城市，國家等

For example:

(a) Tom, a college professor, recently made up his mind to run for the next Mayor's election.

=> Tom (名詞) 與 a college professor 是同位語

(b) Taipei, Taiwan, boasts having the best seafood in the world.

(c) I just came back from Las Vegas, an internationally renowned resort city for gambling. 

N.  Use a comma to set off non-essential elements of the sentence (a non-restrictive clause).  Do not use a comma to set off a restrictive clause.

用逗點隔開句子中的非必要的資料

For example:

(a) Vegetable, which is good for your health, should be eaten everyday.

= Vegetable should be eaten everyday.

=> Vegetable (名詞) 主詞. 

Which is good for your health 句子中的非必要的資料(用來形容主詞 Vegetable) , 可省略.

O.  Use a comma to indicate the omission of a word or words.

(a)  Riding on the same boat requires a decade of cultivation; whilst, sharing the same pillow, a lifetime.

=> sharing the same pillow requires a lifetime of cultivation.

十年修得同船渡 百年修得共枕眠

P.  Use a comma to separate the statement from a question.

(a)  John is coming to the party, isn’t he?

(b)  Give it up, won’t you?

Q.  Use a comma to set off items in dates (excluding the month and day)

(a)  I can’t believe that it is already May 30, 2009.  My son has almost completed his kindergarten year.