stack.pop(); // 弹出无效元素
Apple offers great ways to save on the latest iPad. Customers can trade in their current iPad and get credit toward a new one by visiting the Apple Store online, the Apple Store app, or an Apple Store location. To see what their device is worth, and for terms and conditions, customers can visit apple.com/shop/trade-in.
，这一点在新收录的资料中也有详细论述
在“硬件”层面，部分山区的水库建设、水利设施防控承载能力不强。一些地区因为多年未出现洪水，庄稼、树木、房屋占用了行洪河道，人为削弱了防洪抗涝能力。
吴丰礼：具身智能的发展依赖于本体形态、应用场景、智能模型以及核心数据四大核心支撑。而面向具身智能的工业数据基础设施，是支撑我国具身智能产业从技术研发走向规模化落地的关键底座。