为什么我不能在VisualStudio代码中的python 3上安装numpy

Question

我不知道为什么它不起作用，当我在visual studio的终端中运行命令pip install numpy时，会产生以下错误：

pip : The term 'pip' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the spelling of the
 name, or if a path was included, verify that the path is correct and try again.
At line:1 char:1
+ pip install numpy
+ ~~~
    + CategoryInfo          : ObjectNotFound: (pip:String) [], CommandNotFoundException
    + FullyQualifiedErrorId : CommandNotFoundException

请帮忙