I have read http://www.yiiframework.com/wiki/24/creating-a-dependent-dropdown/ (Dependen Dropdown Yii1), but I can't implement it in Yii2 because Yii2 does not have built-in AJAX functionality hem.. I searched about it and came across this post
Countries sometimes change their laws pertaining to time zones and daylight saving times. This means that GMT+2 can be a different local time this August compared to last August! It could even be a different date!