Generally, commas aren't needed when there are only two short clauses.

The GMAT will never test you JUST on punctuation.

rx_11 wrote:Hi, everyone,

I have some questions about "and". Can you help me clarify whether the following sentences are correct or not?

1. Jim washed the bedroom, and he cleaned the window.- Use of "He" is wordy.

2. Jim washed the bedroom and he cleaned the window - Use of "He" is wordy.

3. Jim washed the bedroom, and cleaned the window-

4. Jim washed the bedroom and cleaned the window-More APt.

Which of the sentense is correct? Experts plz help !

Suppose the sentence was something like this:-
Jim had a red,blue,and green bag. [It means Jim had 3 bags]
Jim had a red,blue and green bag.[It means Jim had 2 bags-One is red and the other bag has 2 colors(blue and green)]

So we have to look into the context to gauge of the sentence.

Anyways,I have hardly seen any OG question solely testing you on punctuation.Nevertheless,it is good to keep the concepts in mind(In case,we can use as a secondary error to rule out that particular sentence)

Laura GMAT Tutor wrote:Generally, commas aren't needed when there are only two short clauses.

The GMAT will never test you JUST on punctuation.

Commas are sometimes there only to make the "joints" clear when clauses are connected via a conjunction. They aren't necessary in such short sentences when the only purpose is separating those short clauses.

the e-gmat lecture said that "comma+and" not "and" is used to connect 2 independent clauses and question 137 og 13 shows this point.

generally, we use "comma+FANSBOY" to connect 2 independent clauses.

in other cases, "and" not " comma+and" is used.