Which of these is a valid differentiated services PHB？ （） ["Guaranteed PHB","Class-Selector PHB","Reserved Forwarding PHB","Discard Eligible PHB","Priority PHB"]
国际定期贷款
铁路运输收入“少缴款”的处理期限为（） ["10天","20天","30天","40天"]
简述教育策划的原则。
特种设备有关制度不健全，属于（）问题。 ["红线","A1","A2","B"]
班主任应如何对学生进行学习指导？
