What are the seven-character palindromes?

Li Qingzhao, a famous poetess in the Song Dynasty, and her husband Zhao Mingcheng are like-minded, and often sing with each other. On one occasion, Zhao Mingcheng managed to write a seven-character palindrome. After reading it, Li Qingzhao immediately wrote a seven-character palindrome. Zhao Mingcheng saw, can't help but admit defeat. Please write Zhao Mingcheng's seven-character palindrome. In autumn, Chu Yan stayed in the sandbar and Yan stayed in the shallow water of the sandbar. In shallow water, the sand goose lives in the continent and the sand goose lives in the river in autumn.