2, once the sea was difficult for water, amber forever. -Yuan Zhen's Lisi
3. When will the Hundred Rivers enter the sea in the east and return to the west? -Yuefu poetry
4. Idioms describing the sea include boundless sea, looking for a needle in a haystack, human will, braving the wind and waves, the ends of the earth, the dust in the East China Sea, a sea of people, measuring the sea with evil eyes, all over the world, all over the world and so on.