E:\phpStudy\WWW>php composer.phar require yiisoft/yii2-gii 2.0.4
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Installation request for yiisoft/yii2-gii 2.0.4 -> satisfiable by yiisoft/yii2-gii[2.0.4].
    - yiisoft/yii2-gii 2.0.4 requires bower-asset/typeahead.js 0.10.* -> no matching package found.

Potential causes:
 - A typo in the package name
 - The package is not available in a stable-enough version according to your minimum-stability setting
   see <https://getcomposer.org/doc/04-schema.md#minimum-stability> for more details.

Read <https://getcomposer.org/doc/articles/troubleshooting.md> for further common problems.

Installation failed, reverting ./composer.json to its original content.

老师帮忙看下是什么问题 composer.phar下载扩展失败？