Scala sources in intellij

After importing the scala source 2.13.x, it can’t work in intellij that code checked by the inspection .
Just like this

It’s my environment.

IntelliJ IDEA 2018.3 (Community Edition)
Build #IC-183.4284.148, built on November 21, 2018
JRE: 1.8.0_152-release-1343-b15 amd64
JVM: OpenJDK 64-Bit Server VM by JetBrains s.r.o
Linux 4.4.0-139-generic

There’s also no use to execute the Developing Scala in IntelliJ IDEA .

How to deal , Thanks for your help

Did you activate the Scala plugin?

Yes, I might have realized how to deal with it.
Intellij 183 version was been installed over the 173 version, but there are some file(conf, cache) retrieved can’t correspond with the 183 version. These have to be cleaned.

Thanks for your help!