In order to advance the development of Yancheng, the city government tries to beautify it as soon as possible. Several new special projects are ______.

A．under construct

B．under building

C．under way

D．under repair

在上学的路上，先以υ₁的速度走完前一半路程，又以υ₂走完后一半路程，则他在上学的全程中平均速度为

A．

B．

C．

D．