Requirement Checker警告 [ 2.0 版本 ]

conclusion说Your server configuration satisfies the minimum requirements by this application.

但是有warning：

Intl extension 	Warning 	Internationalization support 	PHP Intl extension 1.0.2 or higher is required when you want to use advanced parameters formatting in Yii::t(), non-latin languages with Inflector::slug(), IDN-feature of EmailValidator or UrlValidator or the yii\i18n\Formatter class.

ICU version 	Warning 	Internationalization support 	ICU 49.0 or higher is required when you want to use # placeholder in plural rules (for example, plural in Formatter::asRelativeTime()) in the yii\i18n\Formatter class. Your current ICU version is INTL_ICU_VERSION. 

这个应该怎么解决呢？