前几天接手研究生师兄的flutter项目，需要切换低版本的flutter,于是下载了fvm，下载版本后切换一直卡在

PS C:\Users\zyh16> fvm install 2.10.5
✓ Flutter SDK: SDK Version : 2.10.5 installed! (17.2s)
PS C:\Users\zyh16> fvm use 2.10.5

No pubspec.yaml detected in this directory
✔ Would you like to continue? · yes                                                                                    
Setting up Flutter SDK: 2.10.5

Checking Dart SDK version...
Downloading Dart SDK from Flutter engine ...
Expanding downloaded archive...
Building flutter tool...
Running pub upgrade...

更换代理也没用，临时环境变量也不生效

然后添加系统环境变量后解决

PUB_HOSTED_URL https://pub.flutter-io.cn

FLUTTER_STORAGE_BASE_URL https://storage.flutter-io.cn