All of us know that before picking up an answer choice, we need to find out the differences among the answer choices. With a whole underlying sentence, I usually have to read very carefully and slowly each choice to figure out the differences, and this takes me about 2-3 mins.

Could anyone suggest a strategy to find out the differences quickly? Do those long sentences have a specific rule? For me, I see that they usually use "it, they, its, their" to make differences. Anything else can you think of?

Thanks.