Punctuation-Full Stops and Commas
THE FULL STOP OR PERIOD (.) 句點或句號
Full stops (or periods) have two uses. The main use, and the one we all know, is to end a sentence.
The other use is for abbreviations. If the abbreviation relates to a name, a full stop should be placed after each letter. For example, the British Broadcasting Corporation is abbreviated to B.B.C. However, if the abbreviation is an acronym (forms a word in its own right) then the full stops are omitted. For example, the United Nations Educational, Scientific and Cultural Organization is abbreviated to, and called UNESCO.
Shortened forms of words take a full stop after the last letter, as in Mr. and Mrs. That said, some people advocate that if the last letter of the abbreviation is the same as the last letter of the full word as in Mister (Mr), the full stop is not required; again, a matter of style.
The most commonly used abbreviations derived from Latin take the following form:
e.g. i.e. and etc.
THE COMMA (,) 逗號
Commas can be used to separate independent clauses in a sentence. For example: “I had finished my work early, I was hungry, and so I went home.”
Commas are also used after introductory words, phrases or clauses that come before the main clause. For example: “As I was getting ready to go home, my boss came into the office and gave me more work to do.” Remember; if you reverse the order of the clauses, you do not need the comma. Thus: “I went home because I had finished my work early.” “My boss came into the office and gave me more work to do as I was getting ready to go home.” If you are not sure about this, look up sentence structure in the syntax section of any good grammar book.
Commas can be used in pairs to separate extra information from the main body of a sentence. For example: “This note about commas is really useful, as well as interesting, and will help improve my writing.” Remember; if you remove the detail contained between the commas, the remaining sentence should still be grammatically correct and make sense. For example: “My brother, who is ten years older than me, is a doctor.” is still perfectly OK without the reference to my brother being ten years older than me. Do not use commas to separate essential elements of the sentence. For example: “People who eat too much tend to get fat.” has a totally different meaning to “People, who eat too much, tend to get fat.” If you are not sure about this point, look up “defining and non-defining relative clauses” in a grammar book.
The Oxford comma, which is sometimes called a serial comma, was introduced by Oxford University Press and is used to separate all items in a list of three (or more). For example: “I need to buy more paper, stamps, and envelopes.” The comma after the penultimate item (stamps) is the Oxford comma.
Some people prefer not to use a comma in this position, but leaving it out can sometimes lead to confusion. Consider the following: five people (one couple and three individuals) are coming to my party; Jim, Jean, Bob and Mary and Ralph. But, is the couple Bob and Mary, or Mary and Ralph? The Oxford comma solves the problem by eliminating any confusion. So: Jim, Jean, Bob, and Mary and Ralph are coming to my party; Mary and Ralph effectively becoming one item in the list. Alternatively, Jim, Jean, Bob and Mary, and Ralph would be correct were Bob and Mary the couple.
When in any doubt, if adding a comma will make what you are writing clearer and easier to understand, use one!