下列选项中填入横线处恰当的一项是  

___________诗人站在历史的制高点上，看到了国不分强弱，家不分贫富，都应该坚持勤俭节约这一原则。历史和现实也正是如此，经济落后之国，固然要讲究勤俭节约，经济发达之国同样需要节约。

A．“从俭入奢易，从奢人俭难，勤俭建国，永远是真理。”

B．“奢者富不足，俭者贫有余。”

C．“历览前贤国与家，成由勤俭败由奢。”

D．“惰而奢则贫，力而俭则富。”

A work breakdown structure (WBS) is a tool used to define and group a project's discrete work elements in a way that helps organize and define the total work scope of the project. A WBS is most useful for（）

A.identify ingindividual tasks for a project

B.scheduling the startoftasks

C.scheduling the end oftasks

D.determining potential delays