原因： 加入implementation 'com.google.firebase:firebase-analytics时，一直提示冲突：
解决方案： 运行gradlew :app:dependencies >C:\Users\hgy413\Desktop\fa\a.txt打印依赖，搜索上面的play-services-measurement-base, 结果如下：
+--- project :ads | +--- com.facebook.android:audience-network-sdk:5.4.0 | | \--- com.google.android.gms:play-services-basement:11.0.4 -> 16.0.1 | | \--- com.android.support:support-v4:26.1.0 -> 28.0.0 (*) | +--- com.google.android.gms:play-services-ads:17.2.1 | | +--- com.android.support:customtabs:26.1.0 -> 27.0.2 (*) | | +--- com.google.android.gms:play-services-ads-base:[17.2.1] -> 17.2.1 | | +--- com.google.android.gms:play-services-ads-identifier:16.0.0 | | | \--- com.google.android.gms:play-services-basement:16.0.1 (*) | | +--- com.google.android.gms:play-services-ads-lite:[17.2.1] -> 17.2.1 | | | +--- com.google.android.gms:play-services-ads-base:[17.2.1] -> 17.2.1 | | | +--- com.google.android.gms:play-services-basement:16.0.1 (*) | | | \--- com.google.android.gms:play-services-measurement-sdk-api:16.3.0 | | | +--- com.google.android.gms:play-services-basement:16.0.1 (*) | | | \--- com.google.android.gms:play-services-measurement-base:[16.3.0] -> 16.3.0 | | | \--- com.google.android.gms:play-services-basement:16.0.1 (*)多试试，就发现使用 implementation 'com.google.firebase:firebase-analytics:16.3.0'， 如下：
\--- com.google.firebase:firebase-analytics:16.3.0 +--- com.google.android.gms:play-services-basement:16.0.1 (*) +--- com.google.android.gms:play-services-measurement-api:[16.3.0] -> 16.3.0 | +--- com.google.android.gms:play-services-ads-identifier:16.0.0 (*) | +--- com.google.android.gms:play-services-basement:16.0.1 (*) | +--- com.google.android.gms:play-services-measurement-base:[16.3.0] -> 16.3.0 (*) | +--- com.google.android.gms:play-services-stats:16.0.1 (*) | +--- com.google.android.gms:play-services-tasks:16.0.1 (*) | +--- com.google.firebase:firebase-analytics-impl:[16.3.0] -> 16.3.0 | | +--- com.google.android.gms:play-services-ads-identifier:16.0.0 (*) | | +--- com.google.android.gms:play-services-basement:16.0.1 (*) | | +--- com.google.android.gms:play-services-measurement-base:[16.3.0] -> 16.3.0 (*)参考： Firebase引用版本冲突解决：Android dependency ‘com.google.android.gms:play-services-basement’ has different
