YOU SAID:

I wonder who wrote this, and why.

INTO JAPANESE

私は誰がこれを書いたのだろうか、そしてなぜそれが疑問だ。

BACK INTO ENGLISH

I wonder who wrote this, and why that is questionable.

INTO JAPANESE

私は誰がこれを書いたのだろうと思っています。なぜそれが疑わしいのですか？

BACK INTO ENGLISH

I wonder who wrote this. Why is it suspicious?

INTO JAPANESE

誰がこれを書いたのだろうか。なぜそれが疑わしいのですか？

BACK INTO ENGLISH

Who wrote this? Why is it suspicious?

INTO JAPANESE

誰がこれを書いた？なぜそれが疑わしいのですか？

BACK INTO ENGLISH

Who wrote this? Why is it suspicious?