如果你只能上国内的网站，然后你又需要sync gradle，那你需要加标红的内容，再sync就能成功

buildscript {
    repositories {
        maven {
            url "https://maven.aliyun.com/repository/jcenter"
        }
        maven {
            url "https://maven.aliyun.com/repository/google"
        }
        google()
        jcenter()

    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.4.1'
    }
}

allprojects {
    repositories {
        maven {
            url "https://maven.aliyun.com/repository/jcenter"
        }
        maven {
            url "https://maven.aliyun.com/repository/google"
        }
        jcenter()
        google()
    }
}