YOU SAID:

she sells sea shells on the sea shore, if she sells sea shells on the sea shore then she must sell sea shore shells

INTO JAPANESE

彼女が海岸で海貝を売るなら、彼女が海岸で海貝を売るならば、彼女は海岸で海貝を売らなければならない

BACK INTO ENGLISH

If she sells seashells on the coast, if she sells seashells on the coast, she must sell them on the coast

INTO JAPANESE

海岸で貝殻を売る場合、海岸で貝殻を売る場合、海岸で貝殻を売らなければならない

BACK INTO ENGLISH

If you sell seashells on the coast, if you sell seashells on the coast, you must sell seashells on the coast

INTO JAPANESE

海岸で貝殻を売る場合、海岸で貝殻を売る場合、海岸で貝殻を売らなければならない。

BACK INTO ENGLISH

When selling seashells on the coast, when selling seashells on the coast, the seashells must be sold on the coast.

INTO JAPANESE

海岸で貝殻を販売する場合、海岸で貝殻を販売する場合は、海岸で貝殻を販売しなければなりません。

BACK INTO ENGLISH

If you sell seashells on the coast, if you sell seashells on the coast, you must sell seashells on the coast.

INTO JAPANESE

海岸で貝殻を売る場合、海岸で貝殻を売る場合、海岸で貝殻を売らなければなりません。

BACK INTO ENGLISH

If you sell seashells on the coast, if you sell seashells on the coast, you must sell seashells on the coast.