it's crab, isn't doesn't a it?

Question

如题所述

Answer 1

it's crab, isn't doesn't a it?
是连词成句吧，
应该是：
it's a crab, isn't it?
意思是：
这个（东西，动物）是一只螃蟹，不是吗？
主句是系表结构，助动词是is，问句使用is not 提问。