The reason I can tell you what opportunity cost is, is because one day when I was playing Super Mario Kart on my couch, my friend Emmet walked in, and he said, "How long have you been playing Super Mario Kart?"
而我知道什么是“机会成本”，是因为 有一天我躺在沙发上玩“超级玛丽赛车”， 我的朋友艾米特走进来说， “你在这玩 ‘超级玛丽赛车’ 多久了？”