用这些a an are is these this it's what回答下面问题

用这些a an are is these this it's what回答下面问题1.what (is) this?----this is an arm 2.what is (it's)?----It's (a)hand 3.what (are)these?-----(these)are feet 4.(what)is this ---------(this)hair 我做的哪一些对呀?