What do you want to be when you grow up?这里为什么要用to be?

what () you want to do? What do you want to what do you want to do~ What do you want to do three? what do you want me to do What do you want to do three? what do you want to do What are you do what are you want to do What else do you want to do.改为同义句 What ( ) ( ) do you want to do. what do you want to do today.what do you want to do what do you want to say what club do you want to zhe what do you want to know What food do you want to get? what you want to do expect that what do you really want to What do you want to wear? What do you want to be?英语翻译