Poor user interface. Marked questions cannot be viewed alone. It is not apparent that if you leave the study mode you will loose all your marked questions. They obviously didnt use their own software... 5/25/15: addition. You have to be kidding me. Through the first section and no way once you exit to review marked questions, so I started again. Halfway through and when I entered the app again at work, it erased my progress and I have to start again. Critical time wasted. Dont buy this app until they fix this crap! 6/2/15: unbelievable! Went through second section last night. 212 questions with many marked for review. Left the app open when I went to bed to bypass the save and exit feature since it doesnt seem to work. This morning, I was on the home screen without the resume button available. Lost all that progress! There cant be a worst app in the store! 6/9/15: called to complain. The response, "its not happening on mine and no one else has reported it". Pathetic. Today, reviewing the last section, weather. After saving and exiting, with 45 questions reviewed, returned using resume later this afternoon to find myself in the previous section which was already fully completed and reviewed the marked questions. Another 45 question review lost. Awful user interface. Buggy. Terrible app. Steer well clear! Finally, after speaking with clueless support rep, wrote long email outlining problems. The company didnt respond. Ill never use another one of their products or recommend them to anyone ever again.