YOU SAID:

I wish that I knew what to do about this

INTO JAPANESE

私はこれについて何をすべきかを知っていたらいいのに

BACK INTO ENGLISH

I wish I knew what to do about this

INTO JAPANESE

私はこれについて何をすべきかを知っていればいいのに

BACK INTO ENGLISH

I should have known what to do about this.

INTO JAPANESE

私はこれについて何をすべきかを知っていたはずです。

BACK INTO ENGLISH

I should have known what to do about this.