how old is your sister的同义句,who is your best friend同义句

What's your sister's age?你妹妹多大了?

英语中"age"意思是"年龄"，是个名词。此用法类似于What's your name? What's your age?

你妹妹的年龄要用到名词所有格，即名词后加's，某人的。类似于my sister's name.

原句how old引导的特殊疑问句问的是年龄，与What's your sister's age同义