On the pencil-and-paper test there was a way to figure out which section was experimental. And, of course, there is little trick to test-takers. On the computer adaptive test, however, it's very hard to figure out which questions are experimental, and I don't suggest that you try. I can occasionally figure them out because I know the curriculum so well that anything new stands out as a concept ETS is probably experimenting with. But unless you have eight years to study this nonsense, it's probably best that you just focus on answering the questions.