年号是常用的纪年方式。它可以用来指称皇帝，如雍正皇帝；也可以用来表示历史事件，如贞观之治。下列选项符合后一种用法的是

A．辛亥革命

B．商鞅变法

C．靖康之变

D．光武中兴

Although many of the houses in the small town ______ still in need of repair, there _____ lots of

improvement in their appearance. [ ]

A. are, has been    

B. is, have been      

C. is, are          

D. are, was