20200312更新 .net4.5微软官方下载地址(离线安装包) https://download.microsoft.com/download/E/2/1/E21644B5-2DF2-47C2-91BD-63C560427900/NDP452-KB2901907-x86-x64-AllOS-ENU.exe
https://xingfuemo.lanzoui.com/i6zka2d
官网下载 https://download.microsoft.com/download/9/5/A/95A9616B-7A37-4AF6-BC36-D6EA96C8DAAE/dotNetFx40_Full_x86_x64.exe