thanks guys... with little research/search on net- i found
When a coordinating conjunction joins two independent clauses, you must put a comma before the conjunction.
Ø June is a wonderful month, and we also get out of school.
Because "we get out of school" is a complete sentence coming after the "and", you need to put a comma before the "and".
However, if there's not a complete IC on the right side of the 'and', you do not use a comma there.
Ø Mary is nice and smart. ("and" joins two adjectives so there's no comma before the 'and')
Ø Tom went to the store and bought a cola. (bought a cola is not an IC because there's no subject, so there's no comma before the 'and'.)
You can also join to ICs together by using a semicolon instead of a conjunction:
Ø Tigers have stripes; they also have long teeth.
This is the only time that you should really find yourself using a semicolon.
The Dreaded Comma Splice!
If you try to join to IC's without using a conjunction or a semicolon, you have created a COMMA SPLICE! These should not occur in formal writing.
Therefore, you should never see a sentence punctuated like this:
Mary walks every night, she likes it a lot.
The comma is trying to joing the IC "Mary walks every night" with the IC "she likes it a lot." However, the comma is not a strong enough punctuation mark to do this.
Correctly Punctuated Options:
Mary walks every night, and she like it a lot.
Mary walks every night; she like it a lot.
https://swcsimpleandcompound.blocked/
C is comma splice.... it may be corrected if
,and also crafted ( CHANGED TO
and also crafted - see no comma before and)
source:platinum gmat sc.
