Whose is that sweater?中为什么是Whose是表语而不是that sweater

“Whose fork is that whose shirt is that whose bird is that? Whose shirt is that?可以说成Whose is that shirt? whose watch is that?（ ） Whose is that dress?= Whose jacket that is?是什么意思? Whose is that boy?改错 Whose book is that?Whose is that book 这俩 Whose book is that?Whose is that book 这俩 whose ruler is that?同义句whose ruler is that?==?is that 连词成句:that,whose,is,sweater 英语whose bike is that.(同义句) whose is that dictionary.同义句 Whose dolphin is that?同义句是什么? Whose mirror is that?同义句转换 Whose is that book?的同义句 Whose is that car 写出同义句 Whose shirt is that?Whose is that shirt?这两种写法Whose shirt is that?Whose is that shirt?这两种写法都可以吗?