YOU SAID:

i didn't knew duck where this thick

INTO JAPANESE

こんなに厚いところを知らなかった

BACK INTO ENGLISH

I didn't know it was this thick

INTO JAPANESE

こんなに厚いとは知らなかった

BACK INTO ENGLISH

I didn't know it was that thick

INTO JAPANESE

こんなに厚いとは知らなかった

BACK INTO ENGLISH

I didn't know it was that thick