Okay, let's start with timing.
One of the things you should know is that you aren't going to be able to do every single question to the best of your ability. Sometimes, you're just going to have to let something go - you'll still make an educated guess, ideally, but you won't just continue to sit on the problem. The longer you spend, the more likely you are to get it wrong anyway, and you're also guaranteeing yourself others wrong at the end b/c you ran out of time!
So. Figure out whether there are any patterns in terms of the CR types that tend to cost you too much time. Analyze the argument structure (boldface) tends to take a lot of time for most people. And the good news is, these aren't that common on the test. (Most people get either 0 or 1 of these.) So, for these, instead of spending 3+ minutes (and not having great odds re: getting it right anyway), learn how you can eliminate some of the answer choices reliably, do so, guess from among the remaining choices... and move on.
Inference questions are very common on RC and fairly common on CR (sometimes called "draw a conclusion" on CR - but that's the same type), so for those, you'll need to get better. The basic thing to remember is this: when the test asks you to infer or draw a conclusion, what they really want is for you to tell them something that MUST be true, no argument, given the information in the problem / passage. If you have to make even a tiny little assumption - that choice is wrong.
This is tricky because, in the real world, when someone asks you to infer something, they usually do want you to make some assumptions and use your outside knowledge of the topic / world to conclude something that is only plausible, but doesn't have to be 100% true. That is NOT what this test wants. The correct answer has to be something with which you cannot argue - according to the info given in the passage, it's got to work.
For example, I might tell you that chocolate is my favorite flavor of ice cream. In the real world, you might infer that I like chocolate in general, or I like ice cream in general. And, yes, there's a good chance that both of those things are true. But they don't HAVE to be definitely true, without a doubt. What is true, without a doubt, is that vanilla is not my favorite flavor of ice cream. I've already said chocolate's my favorite and, by definition, you only have one favorite. (I know we sometimes say we have two favorites - but that's not consistent with the definition of "favorite.")
Finally, on your item #2, start studying why wrong answers are wrong. Maybe, on a "weaken the conclusion" question, you have a choice that addresses one of the premises, but doesn't actually affect the conclusion. It's tempting because it does address a given premise - it's got all the right keywords, etc. But the question asked us to weaken the conclusion... so any choices that don't actually affect the conclusion can't be right.
Play this game: for every problem you study from now on (you can do this with RC too), ask yourself, "Of the 4 wrong answers, which one do I think is the most commonly chosen wrong answer and why? Why is it so tempting? And why is it wrong even though it's so tempting?" You can even post problems here and ask people to weigh in - what do they think is most tempting (but wrong) and why? That will help you to start to identify WRONG answers (in particular, the tempting ones) with confidence.
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Stacey Koprince
GMAT Instructor
Director of Online Community
Manhattan GMAT
Contributor to Beat The GMAT!
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