The work ________ ahead of the schedule，they went to the seaside to have some fun.[ ]

A．had been finished  

B．has finished

C．having been finished  

D．being finished

提高效率，促进公平，是经济学家和社会学家讨论的永恒话题。关于效率与公平，下列说法中合理的是 [ ]

A．工资薪金所得实行超额累进税率，符合效率原则

B．根据收入多少确定个税的不同税率，符合公平原则

C．基于公平原则，个税征缴应做到平均纳税

D．基于效率原则，个税征缴应缩小纳税差异