The concept of probably approximately correct (PAC) learning has been foundational in computational learning theory.
可能近似正确（PAC）学习的概念在计算学习理论中具有基础性意义。
【大意】一定要等到西施、毛嫱那样的美女作配偶，那么就终身不能成家了。
Coal isn't just a commodity; it's the foundation upon which modern civilization was built.
技术是我们寻求更清洁、更高效能源解决方案的伟大推动者。