和引导疑问句的时候 成分一样啊!
How are you?做表语
How old are you?副词修饰old,how old整个做表语
同样I don't know how you are.I don't know how old you are.中how 的用法没变!不对啊!改成： Would you please tell me the way to the zoo? 或者 Would you please how to get to the zoon?