Laravel項目安裝驗證碼mews/captcha擴展，出現如下錯誤信息：

composer require mews/captcha

Using version ^2.2 for mews/captcha
./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
    - mews/captcha 2.2.0 requires intervention/image ~2.2 -> satisfiable by intervention/image[2.2.0, 2.2.1, 2.2.2, 2.3.0, 2.3.1, 2.3.10, 2.3.11, 2.3.12, 2.3.13, 2.3.14, 2.3.2, 2.3.3, 2.3.4, 2.3.5, 2.3.6
, 2.3.7, 2.3.8, 2.3.9, 2.4.0, 2.4.1, 2.4.2, 2.4.x-dev].
    ..........
    - intervention/image 2.2.1 requires ext-fileinfo * -> the requested PHP extension fileinfo is missing from your system.
    - intervention/image 2.2.0 requires ext-fileinfo * -> the requested PHP extension fileinfo is missing from your system.
    - Installation request for mews/captcha ^2.2 -> satisfiable by mews/captcha[2.2.0, 2.2.1, 2.2.2, 2.2.3, 2.2.4].

  To enable extensions, verify that they are enabled in your .ini files:
    - D:\phpStudy\PHPTutorial\php\php-7.2.1-nts\php.ini
  You can also run `php --ini` inside terminal to see which files are used by PHP in CLI mode.

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

查找原因是php需要開啟fileinfo擴展，

編輯php.ini文件，打開extension=php_fileinfo.dll 就可以了，重新運行composer命令，安裝成功

composer require mews/captcha

Using version ^2.2 for mews/captcha
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
Package operations: 2 installs, 0 updates, 0 removals
  - Installing intervention/image (2.4.2): Downloading (100%)
  - Installing mews/captcha (2.2.4): Downloading (100%)
intervention/image suggests installing ext-imagick (to use Imagick based image processing.)
intervention/image suggests installing intervention/imagecache (Caching extension for the Intervention Image library)
Writing lock file
Generating optimized autoload files
> Illuminate\Foundation\ComposerScripts::postAutoloadDump
> @php artisan package:discover --ansi
Discovered Package: beyondcode/laravel-dump-server
Discovered Package: fideloper/proxy
Discovered Package: intervention/image
Discovered Package: laravel/nexmo-notification-channel
Discovered Package: laravel/slack-notification-channel
Discovered Package: laravel/tinker
Discovered Package: mews/captcha
Discovered Package: nesbot/carbon
Discovered Package: nunomaduro/collision
Package manifest generated successfully.