it's not my...和 it isn’t my.

it's not my...和 it isn’t my. It's not my fault可不可以改成It isn't my fault? it isn't my shirt 与it's not my shirt有什么不同 it isn't your pen,is it?A Yes,it's not mine B No,it's my fri this is not my ... 和 it isn‘t my ... 有什么区别么? it's not和it isn't有什么差别? it isn't和it's not的区别 it isn't =it's not It's not = It isn't The pencil isn’t m___,it's my sister It’s not my fault. It isn't=It is It's not=It is It isn't=It's