"Why do you want to go to Spain?"
This doesn't feel very natural at all. Normally when someone asks me "why" about something, they put it after 你。
In some questions Duo places 你 before "why" and in some after. And in each question correct solution can be only one (?!). You have to guess coorectly. What is the difference and what is correct?
A friend told me 要 is used when you are going to do something. So I think it would translate out to 'why are you going to Spain'. I still choose wrong between 要 and 想, a lot.
I'm not a native speaker, and only learning chinese from duo, but i think 要 is want in front of nouns and in front of verbs it's closer to will.
I think in some sence you can say that 会 is will-can and 要 is will-want.
But i really want a native speaker to clarify it and tell if i'm right or wrong.