YOU SAID:

why do we have to go to school?

INTO JAPANESE

我々 はなぜ学校に行かなければならないのですか。

BACK INTO ENGLISH

That's why we have to go to school?

INTO JAPANESE

だからこそ私たちは学校に行かなければならないか。

BACK INTO ENGLISH

That's why we have to go to school.

INTO JAPANESE

だからこそ私たちは学校に行かなければなりません。

BACK INTO ENGLISH

That's why we have to go to school.