问为什么我不能运行我的颤振项目，在android中不断得到gradle错误？

EN

    [![\* What went wrong: Could not determine the dependencies of task ':app:mergeDebugAssets'. > Could not resolve all dependencies for configuration ':app:debugRuntimeClasspath'. > Could not create task ':app:minifyReleaseWithR8'. > Failed to find Platform SDK with path: platforms;android-31

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BUILD FAILED in 14s
Exception: Gradle task assembleDebug failed with exit code 1][1]][1]

dependencies {
        classpath 'com.android.tools.build:gradle:7.0.2'//by default it was 4.1.2 but was getting error Mapping new ns http://schemas.android.com/repository/android/common/02 to old ns http://schemas.android.com/repository/android/common/01 so I changed to 7.0.2 considering someone's suggestion
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    }

distributionUrl=https\://services.gradle.org/distributions/gradle-7.0.2-all.zip //before it was gradle-6.7