Yes, you can answer the question and mark it as well. When I took the DAT, I answered every question first time through, but I "marked" the questions that I was not completely certain of the answer. When you get to the end of the section, you can review all "marked" questions. After giving it some time, I was able to confirm my answer or say "no, what was I thinking." Topscore will give you the most realistic test scenario.