自然实验是理解现实世界中因果关系的强大工具。
Natural experiments are a powerful tool for understanding causal relationships in the real world.
"A key insight in computational learning theory is that the complexity of a learning problem is determined by the complexity of the hypothesis space and the amount of data available."
可持续性不是一种趋势，而是乳制品农业的未来。
失去的痛苦是我们为爱的喜悦所付出的代价。