问个问题，昨晚倒腾了一晚上也没搞明白

当我composer global require laravel/valet时，安装不成功
错误见下 请教怎么解决啊 gg 百度 都没什么办法
./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
- Conclusion: don't install symfony/process v3.4.3
- Conclusion: don't install laravel/valet v2.0.6
- Conclusion: remove symfony/process v4.0.3
- Conclusion: don't install symfony/process v3.4.2
- Conclusion: don't install laravel/valet v2.0.5
- Conclusion: don't install laravel/valet v2.0.4
- Conclusion: don't install laravel/valet v2.0.5|don't install symfony/process v4.0.3|install symfony/process v2.7.0|install symfony/process v2.7.1|install symfony/process v2.7.10|install symfony/process v2.7.11|install symfony/process v2.7.12|install symfony/process v2.7.13|install symfony/process v2.7.14|install symfony/process v2.7.15|install symfony/process v2.7.16|install symfony/process v2.7.17|install symfony/process v2.7.18|install symfony/process v2.7.19|install symfony/process v2.7.2|install symfony/process v2.7.20|install symfony/process v2.7.21|install symfony/process v2.7.22|install symfony/process v2.7.23|install symfony/process v2.7.24|install symfony/process v2.7.25|install symfony/process v2.7.26|install symfony/process v2.7.27|install symfony/process v2.7.28|install symfony/process v2.7.29|install symfony/process v2.7.3|install symfony/process v2.7.30|install symfony/process v2.7.31|install symfony/process v2.7.32|install symfony/process v2.7.33|install symfony/process v2.7.34|install symfony/process v2.7.35|install symfony/process v2.7.36|install symfony/process v2.7.37|install symfony/process v2.7.38|install symfony/process v2.7.39|install symfony/process v2.7.4|install symfony/process v2.7.40|install symfony/process v2.7.5|install symfony/process v2.7.6|install symfony/process v2.7.7|install symfony/process v2.7.8|install symfony/process v2.7.9|install symfony/process v2.8.0|install symfony/process v2.8.1|install symfony/process v2.8.10|install symfony/process v2.8.11|install symfony/process v2.8.12|install symfony/process v2.8.13|install symfony/process v2.8.14|install symfony/process v2.8.15|install symfony/process v2.8.16|install symfony/process v2.8.17|install symfony/process v2.8.18|install symfony/process v2.8.19|install symfony/process v2.8.2|install symfony/process v2.8.20|install symfony/process v2.8.21|install symfony/process v2.8.22|install symfony/process v2.8.23|install symfony/process v2.8.24|install symfony/process v2.8.25|install symfony/process v2.8.26|install symfony/process v2.8.27|install symfony/process v2.8.28|install symfony/process v2.8.29|install symfony/process v2.8.3|install symfony/process v2.8.30|install symfony/process v2.8.31|install symfony/process v2.8.32|install symfony/process v2.8.33|install symfony/process v2.8.4|install symfony/process v2.8.5|install symfony/process v2.8.6|install symfony/process v2.8.7|install symfony/process v2.8.8|install symfony/process v2.8.9|install symfony/process v3.0.0|install symfony/process v3.0.1|install symfony/process v3.0.2|install symfony/process v3.0.3|install symfony/process v3.0.4|install symfony/process v3.0.5|install symfony/process v3.0.6|install symfony/process v3.0.7|install symfony/process v3.0.8|install symfony/process v3.0.9|install symfony/process v3.1.0|install symfony/process v3.1.1|install symfony/process v3.1.10|install symfony/process v3.1.2|install symfony/process v3.1.3|install symfony/process v3.1.4|install symfony/process v3.1.5|install symfony/process v3.1.6|install symfony/process v3.1.7|install symfony/process v3.1.8|install symfony/process v3.1.9|install symfony/process v3.2.0|install