GMAT Sentence Correction (SC) | Because natural gas is composed mostly of methane, a simple

Hi Verbal Expert,

Most of the time, I solve comparison questions wrong. Probably, there is a lack of understanding of this concept.
I find it difficult where omission of some words will make the sentence incorrect and where it will not. Please explain. Thanks

I read one post earlier with the below examples on Comparison
more babies were born to women over the age of thirty than under the age of 30

more babies were born to women over the age of thirty than to women under 30

more babies were
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