"previousInventoryETag": "5800c7d6-0000-0800-0000-6982949c0000",
其他重要内容：油价创数十年来最大单周涨幅，高盛称油价下周或突破100美元
。新收录的资料对此有专业解读
A filled torus (a doughnut) is a 3-manifold homeomorphic to \(S^1 \times D^2\), where \(D^2\) is the 2-dimensional disk. There exists a deformation retract from the doughnut to a circle, so the fundamental group of the doughnut is \(\pi_1(S^1 \times D^2) \cong \mathbb{Z}\).
Что думаешь? Оцени!，这一点在新收录的资料中也有详细论述
https://feedx.site
What is this page?。业内人士推荐新收录的资料作为进阶阅读