YOU SAID:
she sells seashells on the seashore, the seashells she sells are seashore seashells
INTO JAPANESE
彼女は海岸で貝殻を販売しています、彼女が販売している貝殻は海岸の貝殻です。
BACK INTO ENGLISH
She sells shells on the coast, the shell she sells is the seashell on the coast.
INTO JAPANESE
彼女は海岸で貝殻を売っています、彼女が売っている貝殻は海岸で貝殻です。
BACK INTO ENGLISH
She sells shells on the coast, the shell she is selling is a shell at the coast.
INTO JAPANESE
彼女は海岸で貝殻を売っています、彼女が売っている貝殻は海岸で貝殻です。
BACK INTO ENGLISH
She sells shells on the coast, the shell she is selling is a shell at the coast.
That didn't even make that much sense in English.