You just didn't get the hang of it for a while.

If you are a diligent person. I'll tell you a stupid way to do different kinds of problems over and over again. Until you master it yourself. This method is firm.

Another one is to ask others. Teachers and students can ask questions, as long as they get through. This is about overcoming shyness ~ ~

The combination of the two is the best to talk about. . .