ll com.android.support libraries must use the exact same version
specification (mixing versions can lead to runtime crashes). Found versions 28.0.0-alpha1, 26.1.0. Examples include com.android.support:animated-vector-drawable:28.0.0-alpha1 and com.android.support:customtabs:26.1.0 less... (Ctrl+F1) There are some combinations of libraries, or tools and libraries, that are incompatible, or can lead to bugs. One such incompatibility is compiling with a version of the Android support libraries that is not the latest version (or in particular, a version lower than your targetSdkVersion).
my gradle dependencies:-
implementation 'com.google.firebase:firebase-ads:15.0.1'
implementation 'com.google.firebase:firebase-core:16.0.1'
warning on this dependencies -----------------------------
implementation 'com.android.support:appcompat-v7:28.0.0-alpha1'
testImplementation 'junit:junit:4.12'
implementation 'com.google.android.gms:play-services-vision:15.0.2'
implementation 'com.theartofdev.edmodo:android-image-cropper:2.3.+'
implementation 'com.memetix:microsoft-translator-java-api:0.6.2'
implementation 'com.google.firebase:firebase-crash:16.0.1'
implementation 'com.facebook.android:audience-network-sdk:4.+'