Android Studio , Could not find com.google.android.gms:play

Could not find com.google.android.gms:play-services-ads:11.0.2. Required by: project :
I am trying to compile project on android studio, and I get this error

Could not find com.google.android.gms:play-services-ads:11.0.2.

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I just want to generate the apk, and I don’t understand what cause this behavior.
and i don’t know , what i must do ?

maybe some one ccan help please

>Solution :

try this
Open your SDK Mangerand and check if you have com.google.android.gms:play-services-ads , if not , download

com.google.android.gms:play-services-ads:11.0.2

this will resolve your issue. Thanks