YOU SAID:
The piano fell down the stairs and I don't know
INTO JAPANESE
ピアノが階段から落ちて、私は知らない
BACK INTO ENGLISH
The piano fell down the stairs, I do not know
INTO JAPANESE
ピアノは階段から落ちた、私は知らない
BACK INTO ENGLISH
The piano fell down the stairs, I do not know
You've done this before, haven't you.