YOU SAID:
She sells sea shells on a sea shore and the sea shells she sells are sea shells for sure.
INTO JAPANESE
彼女は海岸で貝殻を売っていて、売っている貝殻は確かに貝殻です。
BACK INTO ENGLISH
She sells shells at the beach, and the shells sold are certainly shells.
INTO JAPANESE
彼女は浜で貝殻を売っています、そして売られた貝殻は確かに殻です。
BACK INTO ENGLISH
She sells shells at the beach, and the shells sold are certainly shells.
You've done this before, haven't you.