for my tests, my teacher has given us a hint that we must be able to know how the causes of WW2 is linked to WW1. will appreciate hel ASAP as it is pretty urgent.

I would imagine that your teacher is refering to the impact of the Treaty Of Versailles on European politics, particularly with Facism in Italy and Germany. The resentments in many nations that there were. Without telling you the answer, no one was happy with the treaty.

Try this site
This one

Just remember, like most things there were short and long term causes, even to do with the influence of world war one.

However in your answer try to be brief and to the point.

Try reading this thread - it's a very similar issue; the answers to that question are the same as they answers to your question.