global void execute(SchedulableContext sc) {
    EmailTemplate template = [SELECT id FROM EmailTemplate WHERE DeveloperName = 'P1_Followup_Remainder'];
    Case cs = new Case();
    if(cs.CLOSED__c==TRUE && cs.Status=='High'){
        Messaging.SingleEmailMessage mailstosend = new Messaging.SingleEmailMessage();
        {

            Messaging.SingleEmailMessage msg = new Messaging.SingleEmailMessage();
            msg.setTemplateId('00X7F000000Dwb7');
            msg.setCcAddresses(new String[] {'ai@gmail.com'});
            msg.setTargetObjectId(cs.Id);
            msg.setSaveAsActivity(false);
            Messaging.sendEmail(new Messaging.SingleEmailMessage[] { msg });
        }
    }
}