四个数字有多少种组合有两个重复

简介：Among them, ancient books record: Tapirs, which came out of Seosan County today, have black and white fur, are as small as bears, can eat snakes, lick iron with their tongues, can swallow dozens of kilograms, and can dissolve iron into water by drowning. If there is iron in the abdomen caused by accidental ingestion, take it and it will disappear by drowning ①. So at that time, some people would also call the cat, bear, and iron-eating beast.