While browsing the homework questions section I find myself unable to answer - for example - some of the 1st/2nd year physics questions and I'm currently in my 3rd year. I could have answered them at the time of studying but now it seems I can only remember the things I'm currently studying. Is this normal? How do the homework helpers manage to remember everything and answer a broad range of physics questions? Do they have superior mental abilities? Would be interested to know if anyone else has this problem. And also how to remember to spell the word learnt.