Trust ALLAH that always you will get good marks but hard work is must. He always helps you. Pray 5 times & read Quran daily with translation and get closer to Allah. There is a story in Masnawi Maulana Roomi that one cow was very nervous that what she will have to eat next day. And she gets thin every day in this nervousness. But when the next day starts she has food and gets fat. But then again thinking about the next day she would become thinner. So there is message in this story that every time you are successful and think negative for the next time. This is not fair.