4) One day the rich man became poor because......( he lost his gold, the thief took his gold, his friends took his gold and sold it)

Чтобы ответить на вопрос, обратимся к тексту произведения "Богач и золото".

В тексте сказано: "Then the thief went to the hole and dug up the gold. «A big piece of gold! » he said. «It's my gold now. I am a rich man. >> He ran off with the gold and never came back."

Следовательно, богач стал бедным, потому что вор забрал его золото.

Ответ: he lost his gold, the thief took his gold, his friends took his gold and sold it