Everyone, thanks for your attention.
I'm using Intellij IDEA 2017.2 in windows 7, with Scala plugin installed.(I downloaded directly from the web and installed it from local disk.)
But when I wanna to add Scala sdk through "Project Structure-Global Libraries" , I clicked the menu "Scala sdk" which is shown in the picture below, it didn't appear by the popup window as expected, i.e, it didn't present anything. So I cannot select the Scala sdk.
the picture describes the scenario
What should I do to make it work in Intellij? My scala version is 2.12.2. Any advices will be appreciated.