I am trying to install that linux subsystem to be part of the test, but when following the instructions on the MS Windows page about Linux subsystem, the first thing they tell you to do is run a long command from Windows powershell. I copied that command and windows comes back with saying the the word "online" is specified more than once. So what is the correct command for the Enable WindowsOptionalFeature?

https://docs.microsoft.com/en-us/windows/wsl/install-win10

"It`s" says : Reboot , in short sentence.