Time to work on commas: People are usually strong, competitive, and physically...

[Aikuzo]

4. People who work with tools or machines are usually strong, competitive, and physically healthy.

5. Bank tellers, secretaries, office managers, and accountants have conventional jobs.

6. People who describe themselves as outgoing, cooperative, helpful, and responsible have social jobs.

Anything errors guys?
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I quit studying English years ago and have just come back to study the basics.

[SkiIucK]

In my opinion, the commas before "and" in 5. and 6. are redundant.

[Alan]

Hi Aikuzo,

The whole point of the comma is to provide a natural break. The use of 'and' in your sentences already provides this. In that sense the comma is therefore not needed because 'and' is doing that job .

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

[Cerberus™]

There are two schools about whether to put this comma before "and": I'd say either choice is right, as long as you stick to it. The comma before "and" is often called the Oxford comma, if I remember correctly.
http://en.wikipedia.org/wiki/Serial_comma