YOU SAID:
She sells seashells by the seashore which caused me to buy a seashell
INTO JAPANESE
彼女は私が貝殻を買う原因となった海岸のそばで貝殻を売っている
BACK INTO ENGLISH
She sells seashells by the beach that caused me to buy shells.
INTO JAPANESE
彼女は私が貝殻を買う原因となったビーチで貝殻を売っています。
BACK INTO ENGLISH
She sells seashells on the beach that caused me to buy them.
INTO JAPANESE
彼女は私がそれらを買う原因となったビーチで貝殻を販売しています。
BACK INTO ENGLISH
She sells seashells on the beach that caused me to buy them.
You've done this before, haven't you.