位于我国地势第三级阶梯上的地形区是[ ]
A．柴达木盆地
B．成都平原
C．黄土高原
D．华北平原
答案：D
—Have you ever ______ Jin Yong?
—Of course, a very famous writer, and he once studied in Quzhou. [ ]
A. heard
B. hearing
C. heard of
D. heard from
用于机场道面维护的特种车辆主要包括清扫车、清水车、吹雪车、扫雪车等。（）
