Using a comma: My brother John, who lives in New York, is a banker.

[Manian]

I do not understand the following 3 sentences
Why is a comma not used in sentence 1 but in sentences 2&3
The man who lives next door is very old.
My brother John,who lives in New York, is a banker.
Thw Swiss,who are famous for their chocolate,are considered to be very hard working.

[Alan]

Hi,

The absence of a comma in sentence one is an example of a defining relative clause/sentence. In two and three the information contained in the relative clause/sentence is additional but not defining

When I write: The man who lives next door .... I am describing/defining that man in contrast to all the other men in the road.

When I write: That man, who is actually Swiss, was telling me about his holiday in France ... I am not selecting him in particular from all the other people, I am telling you an additional piece of information about him.

You might like to look at some material I have written for the site on relative pronouns:

http://www.english-test.net/lessons/21/index.html

http://www.english-test.net/lessons/22/index.html

http://www.english-test.net/lessons/23/index.html

Alan
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English as a Second Language
You can read my ESL story Briefly

[Manian]

Thank you very much