题目

The American population was the tallest in the world from about the American Revolution to World WarⅡ ― that’s a long time. The U.S. had a very resource rich environment, with game, fish and wildlife. In fact we have data on disadvantaged people in America, such as slaves. They were obviously among the most mistreated populations in the world, but given the resource abundance，and given the fact that the slave owners needed their work, they had to be fed relatively fairly well. So the slaves were taller than European peasants. It’s no wonder that Europeans were just flooding to若，则_______.