We’ve already said that if you can eliminate one answer in a question, the scoring odds are in your favor, and you should guess. This means that you shouldn’t skip a question juts because you realize you don’t know the right answer. Before skipping any question, check to see if you can at least eliminate an answer. For every question, you should go through a checklist of priorities:

On most questions, there will be at least one or two answer choices you can eliminate. There are also certain styles of question that lend themselves to particular processes of elimination.

The weakness of classification questions is that the same five answer choices apply to several questions. Invariably, some of these answer choices will be tempting for some questions, but not for others.

For instance, you can be pretty sure that uracil doesn’t appear in protein, carbohydrates, or phospholipids, since nitrogenous bases are only found in RNA and DNA.

Another point that may help you guess in a pinch: you’ll rarely find the same answer choice being correct for two different questions. True, the directions for classification questions explicitly state that an answer choice “may be used once, more than once, or not at all,” but on the whole, the ETS people shy away from the “more than once” possibility. This is by no means a sure bet, but if you’re trying to eliminate answers, you might want to eliminate those choices that you’ve already used on other questions in the same set.

If you’re wondering, the answers to the above questions are 1 E, 2 B, and 3 A. Don’t worry if you didn’t know these answers. After reading this book, you will. The same goes for the following example questions.

“EXCEPT” questions are five-choice multiple-choice questions that contain a bunch of right answers and one wrong answer. The questions always contain an all-caps EXCEPT, LEAST, or some other, similar word. Even if you aren’t sure of the answer (which is actually the wrong answer), you should be able to identify one or two of the answer choices as true statements and eliminate them.

Perhaps you’re not sure which of the five answer choices is wrong. But you should be able to identify that birds do lay eggs protected by shells and that they evolved from dinosaurs. Already, you’ve eliminated two possible answers and can make a pretty good guess from there.

If you’re interested, the answer is B: the bones of birds are extremely light. Heavy bones would make flight much more difficult for birds.

“I, II, and III” questions are multiple-choice questions that provide you with three possible answers, and the five answer choices list different combinations of those three.

There’s an upside and a downside to questions like this. Suppose you know that the scenario described by this question does involve speciation, but you aren’t sure about natural selection or convergent evolution. The downside is that you can’t get the right answer for sure. The upside is that you can eliminate A and B and significantly increase your chance of guessing the right answer. As long as you’re not afraid to guess—and you should never be afraid to guess if you’ve eliminated an answer—these questions shouldn’t be daunting. By the way, the answer is C: changes in organisms’ characteristics due to changes in habitat are a result of natural selection, and the inability of the members of a former population to interbreed after being separated for a long time is speciation.