同学们都很熟悉我国封建皇帝立太子的事情，那么这种事情从什么时候开始的 [ ]
A．舜传位给禹
B．禹传位给启
C．尧传位给舜
D．黄帝打败了蚩尤
答案：B
The transportation has improved a lot in that province, with two new roads ____ last year
A．constructing
B．to construct
C．constructed
D．construct
