好的网络资源

1.基础拓扑学(basic topology)

https://www.bilibili.com/video/BV1P7411N7fW/?spm_id_from=333.1387.homepage.video_card.click&vd_source=ca656fb4f721c1b54202d998d382e357

2.【抽象代数】0. 预备知识与专栏目录

https://zhuanlan.zhihu.com/p/162709824

3.