Igcse edexcel Spanish

The best way to revise a language is not to learn the questions but rather learn how to answer them. This may include learning key words and sentence structure so that you would be able to answer any question that you may be asked.
Especially in speaking there is an unlimited number of questions that you may be asked and it is impossible and time consuming to try and study all of them. However, if you learn key verbs and phrases then you stand a very strong chance of doing well.
Also for writing you can do the same thing as speaking but I would also recommend completing past papers and asking your teacher to mark it as it would allow you to understand where you may have made mistakes or where you need to improve.