Virtually all GMAT Reading Comprehension questions fall into these 6 categories.
1) Find the Main Idea
GMAT asks this question about almost every passage in RC. This is the number-one RC skill, which you need to practice over and over again. It will help to read at a relaxed pace (2.5 minutes for a short RC passage, 3.5 for a long passage). It will help to practice taking notes. It will also help to practice repeatedly, checking the official answers each time and reading the explanation in the OG to understand, whether you got the question right or wrong.
“The role of the second paragraph is …”, “The author mentioned the life cycle of wombats at the end of the first paragraph in order to …”
This is not entirely different from the first question type. The main idea is what informs the entire passage, what drives the whole passage, so any detail mentioned has to support the main idea in some way. To answer a detail question, you need to know the main idea, and you probably will need to go back and re-read those particular sentences to see how it plugs in to the main idea.
Good authors are not explicit about everything: while they say something things directly, they imply others. Inference questions test your ability to read between the lines, to figure out what the author is implying.
On the GMAT be careful to stay hyper-faithful to the passage. Any correct implication is something that was not explicitly stated but must be true. It must be a direct logical consequence of what was said. If the passage says, “Ben has been to every country in Europe at least once”, we can’t necessarily infer that “Ben enjoys traveling” — maybe Ben hates traveling but has had to travel for work, for example. An undeniable implication is: “Ben has been to Portugal at least once.” That’s the level of logical undeniability that you should seek in inference questions answer choices.
4) Out of Context
Some of these questions will present a new concept, one not discussed at all in the text, and ask you what the author would think about it. Here, you need to have deduced from the passage the perspective and preferences of the author in order to answer this question.
The questions may also ask you to compare something in the passage to a hypothetic example from a completely different situation. “The compromised situation of the raccoon described in line X is most like …”, and then the correct answer could be something like “a ballerina with a broken foot.” In these questions, you are asked to abstract out all particulars, and focus on what is essential to the situation or relationship in its most austere logical form.
In both cases, however seemingly remote the focus of the question is, the correct answer should still resonate with the author’s main idea.
5) Logical Structure
Some questions will ask about the structure of the passage as a whole: Does the author present her own new idea? Does the author contrast two ideas, showing evenhandedly the strengths and weaknesses of both? Does the author sharping criticize a particular position or perspective? Sometimes this question is phrased as: what would be the best title for this passage?
Here, the main idea and paragraph summaries you formulate for your notes will be invaluable. Another huge help will be the “logical direction” words — “moreover”, “although”, “ironically”, “but” etc. Always pay attention to these words when you read anything, to the way they shape the passage, and you thereby will start to develop an intuitive sense of the logical structure of passages.
6) Author’s Tone
This is tricky, because unlike the extreme opinions typical of nutcases in the media, all the opinions and perspectives of GMAT authors will be moderated and nuanced. An author who judges something “promising” is wildly enthusiastic about it. An author who deems something “less than satisfactory” is completely slamming it. An author who finds something “troubling” is essentially pee-in-his-pants upset about it. If vivid emotions are bright colors, then GMAT passages don’t get any more colorful than pastels. Pay attention to any words that have any emotional charge: these are the ones that will allow you to figure out the tone.
It’s also important to remember: the tone in the passage will avoid extremes, so the correct answers to tone questions will avoid extremes as well. If the correct answer to a tone question is “skeptical”, wrong answers could include “dismissive” or “vengeful”, words that simply are two extreme for the tenor of GMAT RC.