When I create a new Project in Android Studio I get this problems , I don't Know how to resolve them , I'm using Android Studio Version 3.0.1 enter image description here
Error:Unable to resolve dependency for ':app@debug/compileClasspath': Could not resolve com.android.support:appcompat-v7:26.1.0.
Error:Unable to resolve dependency for ':app@debugAndroidTest/compileClasspath': Could not resolve com.android.support.test:runner:1.0.1.
Error:Unable to resolve dependency for ':app@debugAndroidTest/compileClasspath': Could not resolve com.android.support.test.espresso:espresso-core:3.0.1.
Error:Unable to resolve dependency for ':app@debugAndroidTest/compileClasspath': Could not resolve com.android.support:appcompat-v7:26.1.0.
Error:Unable to resolve dependency for ':app@debugUnitTest/compileClasspath': Could not resolve com.android.support:appcompat-v7:26.1.0.
Error:Unable to resolve dependency for ':app@debugUnitTest/compileClasspath': Could not resolve junit:junit:4.12.
Error:Unable to resolve dependency for ':app@release/compileClasspath': Could not resolve com.android.support:appcompat-v7:26.1.0.
Error:Unable to resolve dependency for ':app@releaseUnitTest/compileClasspath': Could not resolve com.android.support:appcompat-v7:26.1.0.
Error:Unable to resolve dependency for ':app@releaseUnitTest/compileClasspath': Could not resolve junit:junit:4.12.
and about the code there are No Problem in the code , I don't Know ?