In the Manhattan's SC Guide 8, 3rd ed at page 63, I

Question

In the Manhattan's SC Guide 8, 3rd ed at page 63, I understand that if I join 2  main  clauses with  and , I have to put a comma before the  and .

1. Applying this rule, why is it that the following sentence at page 62: - "The division was opening offices, hiring staff and investing in equipment" - that there is no comma after "hiring staff"?

2. How does that differ from the next sentence: - "They wanted to increase awareness, spark interest, and motivate purchases" - wherein there is a comma after "spark interest".

- Applying the logic of this sentence, at page 68 of the same book, why is it that there is no comma after "notify investors" for the "right" sentence under heading (2) Infinitives:- "It is critical to suspend activites, notify investors and say nothing".

Would appreciate any clarifications to the above. Thanks.

bipolarbear · Answer

You're getting confused with main clauses. When you join two main clauses, each clause is in itself a sentence.
E.g. He wanted to go to the party, and then he decided not to.
These are two main clauses, since each clause is in itself a complete sentence.

The two examples you just provided are not main clauses and the and is not used to connect them, but rather the and is used to join a "list of terms." 
E.g. I like donuts, carrots, and ice cream. 
or
I want to go swimming, skiing, and diving.

When using a comma to join a list, it is OPTIONAL to place a comma before the last word of the list. So,

I've been to Canada, Chile, and China.
I've been to Canada, Chile and China.

are BOTH correct.

Hope that makes sense.

tarek99 · Answer

I think also that it depends on whether you're using an American english or the British english. From what I understand, the british english doesn't favor using a coma before "and" in a list. The american english, however, tends to favor adding a comma before "and" in a list. but sometimes you can find both approaches are used even in the american english, so it's interesting to read your explanation.

In the Manhattan's SC Guide 8, 3rd ed at page 63, I

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