what's the special today? 和what special day is today?都对!
但what kind is the fish? 对,what's the kind of the fish? 不对
因为：
what special day is today?
what kind is the fish?
what day is today?属于同一种用法,
但what's the special today?是歪打正着的
因为what's the date today中的date是名词,而what's the special today?中的special是形容词,不是同一种用法.
what's the special today?可解释为：今天有什么特殊的?所以也说得过去