Japanese sentence structure
I'm very beginner at Japanese, and am a little confused at some of the sentence structure. For example, why is the topic "red car" in the sentence "aka no kuruma wa anata no desu ka?" but not "pink house" in the sentence "dare no pinku no ie desu ka?" - instead, the topic seems to be "whose". How is the sentence topic dictated? I'm sorry if this is worded badly!