Android Studio 无法解析：com.android.support:appcompa

Question

我收到此错误，无法解决：com.android.support:appcompat-v7.28.0.0 我一直在这里查看并尝试将其更改为该行的其他变体，但到目前为止没有运气，为什么我一直收到这个错误？

apply plugin: 'com.android.application'

android {

compileSdkVersion 28

defaultConfig {

    applicationId "com.example.myapp"

    minSdkVersion 15

    targetSdkVersion 28

    versionCode 1

    versionName "1.0"

    testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"

}

buildTypes {

    release {

        minifyEnabled false

        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'

     }

 }

}

dependencies {

implementation fileTree(dir: 'libs', include: ['*.jar'])

implementation 'com.android.support:appcompat-v7.28.0.0'

implementation 'com.android.support.constraint:constraint-layout:1.1.3'

implementation 'com.google.firebase:firebase-auth:11.6.0'

implementation 'com.google.firebase:firebase-core:16.0.3'

implementation 'com.google.firebase:firebase-database:16.0.1'

testImplementation 'junit:junit:4.12'

androidTestImplementation 'com.android.support.test:runner:1.0.2'

androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'

}

apply plugin: 'com.google.gms.google-services'