Could not GET 'https://dl.google.com/dl/android/maven2/com/android/tools/build/gradle/3.1.3/gradle-3
Andorid studio 3.XX版本出现如下图错误：
即：Could not GET 'https://dl.google.com/dl/android/maven2/com/android/tools/build/gradle/3.1.3/gradle-3.1.3.pom'. Received status code 400 from server: Bad Request
Enable Gradle 'offline mode' and sync project
解决方法：
file ->> setting ->> build，excution，->>gradle ->> android studio ->> 勾选enable。。。 如下图所示：
然后再“try again” 就好啦
