YOU SAID:
shirley is selling sea shells on the sea shore
INTO JAPANESE
シャーリーは海岸で貝殻を売っている
BACK INTO ENGLISH
Shirley sells shells on the beach
INTO JAPANESE
シャーリーは浜辺で貝殻を売る
BACK INTO ENGLISH
Shirley sells shells on the beach
That didn't even make that much sense in English.