Question

That isn't my English teacher.这句话对吗？

Answer 1

that isn't my English teacher.这句话正确
1.that可做为代词，意思是（指较远的人或事物）那， 那个 。
2.that，pron.【不规则形式】 pl. those（指较远的人或事物）那，那个 used for referring to a person or thing that is not near the speaker, or not as near to the speaker as another
例句：
Who's that?
那是谁？
That's Peter over there.
那边那个人是彼得。
Hello. Is that Jo?
喂，是乔吗？
That's a nice dress.
那件连衣裙很漂亮。
Those look riper than these.
那些看上去比这些熟一些。
3.从例句That's Peter over there.那边那个人是彼得来看，that isn't my English teacher.这句话正确。

Answer 2

That person isn't my English teacher.