什么情况：
D:\myphp_www\PHPTutorial\WWW\PHPDemo\laravel>composer create-project laravel/laravel Laravel --prefer-dist "5.5.*"
[InvalidArgumentException]
Could not find package laravel/laravel with version 5.5.* in a version installable using your PHP version 5.4.45.
create-project [-s|--stability STABILITY] [--prefer-source] [--prefer-dist] [--repository REPOSITORY] [--repository-url REPOSITORY
-URL] [--dev] [--no-dev] [--no-custom-installers] [--no-scripts] [--no-progress] [--no-secure-http] [--keep-vcs] [--remove-vcs] [-
-no-install] [--ignore-platform-reqs] [--] [<package>] [<directory>] [<version>]
