YOU SAID:
this is the best thing since sliced bread
INTO JAPANESE
これはスライスされたパン以来最高のものをします。
BACK INTO ENGLISH
This is the best thing since sliced bread.
INTO JAPANESE
これはスライスされたパン以来最高のものです。
BACK INTO ENGLISH
This is the best thing since sliced bread.
That didn't even make that much sense in English.