I don't think the structure is that important. But a basic structure to use for most questions is to answer it, then elaborate and explain the answer that you have.
E.g. Briefly explain two of the factors contributing to the fall of the Weimar Republic.
Answer: The depression and use of presidential powers to undermine democracy were two of the factors involved in the collapse of the Weimar republic. The depression created great poverty in Germany and many germans blamed the newly formed democratic government... yadda yadda yadda. The use of presidential powers also undermined democracy in Germany... blah blah blah.
Get what I mean??
But personally I don't think the structure is hugely important in shorter questions. You just have to make sure that you actually answer the question. Read it carefully and be sure to cover everything it is asking in your response. And try to be succinct.