1. # composer安装Yii2框架，创建basic项目
    2. composer create-project --prefer-dist yiisoft/yii2-app-basic basic
    4. # 报错
    5. Could not find package yiisoft/yii2-app-basic with stability stable. 
    7. # 解决方式：更换composer镜像源
    8. composer config -g repo.packagist composer https://mirrors.aliyun.com/composer/