YOU SAID:

I don't know what is happen

INTO JAPANESE

何が起こるかわからない

BACK INTO ENGLISH

Do not know what will happen?

INTO JAPANESE

何が起こるかわからないですか。

BACK INTO ENGLISH

Do not know what will happen.

INTO JAPANESE

何が起こるかを知っていますか。

BACK INTO ENGLISH

Do you know what happens.

INTO JAPANESE

あなたは何が起こるか知っています。

BACK INTO ENGLISH

I know what happens.

INTO JAPANESE

私は何が起こるか知っています。

BACK INTO ENGLISH

I know what happens.