The key to understanding verbal reasoning is understanding the people who write the GRE.
In order for a question to make it onto the test, it has be fair. ETS is extremely careful to make questions fair and consistent. Verbal questions always play by the same rules. (This is why I never recommend analyzing GRE verbal questions published by any other company than ETS.)
Ok, so what rules?
It's simple. Right answers are either:
Wrong answers have something wrong with them.
So why, you might ask, do I have so much trouble with certain questions? Let's think about reading comprehension for an illustration: right answers are often DISGUISED. Wrong answers are often ATTRACTIVE. Right answers are often slightly vague or general. You might not see the same wording as the passage. That's kind of a good sign. Wrong answers often DO use wording straight from the passage. That's kind of a bad sign.
Your job when you study is to notice why a wrong answer you've picked might be attractive to someone, and to see if the right answer might have been disguised.
Most correct answers are true because they have literal support. A blank for a text completion, for instance, might be supported by a specific descriptive clue. Below is an video example for you (start watching at about 6:40 - I want to you focus on the support for blank iii, which I think is the hardest blank).
When it wrote this question, ETS was careful to make sure there was justification for "discrepancy", and that there wasn't any for "ambiguity" or for "duplicity". The test will never make you choose the "best" answer; one answer will be definitively right and the other choices will be wrong. This goes for passage questions, too. I would even extend this rule to Critical Reasoning questions - I'll explain how it applies to those little guys in a later post.
What about when the GRE asks you to "infer", or asks you which choice is "implied" or "suggested"? Believe it or not, these questions work the same way. One answer will be right, the others, wrong. The big difference is that the right answer may not be in the passage. It may be right because it is unavoidably true based on the passage.
The good news is that the GRE doesn't make you jump too far. There's a question in the Verbal Reasoning Practice Book in a passage about UHECRs (ultra-high-energy cosmic rays) in which the passage tells you that these rays cannot retain their energy much beyond 100 million light years. One of the right answers says something like "the source of the rays we've detected is within 100 million light-years of Earth".
See the inference required? If the rays can't retain their energy beyond 100 million light years, their source must be closer to us than that.
You may find this type of inference easy. It requires a little bit of logic. But some questions of this nature might be hard for people. When you're in doubt, my tip is:
"If it makes sense to you and it would be difficult to prove wrong, it's probably right."
There's a right answer for a question in the Official Guide to the Revised GRE that depends on your ability to infer that one of the functions of a greenhouse's design is to allow sunlight in to help the plants grow. The passage never says anything about that. But doesn't it make sense? It's a freaking greenhouse! It would be difficult to prove wrong, too.
Stay tuned for my next GRE for High Scorers post. Until then, analyze those ETS questions!