我国的基本民族政策是 ( )
A:人民代表大会制
B:民族区域自治制度
C:民族团结
D:共享经济繁荣成果
—What is Mary's mother doing?
—She is d____ her car to work.
I'm afraid ____ out alone at night.
下列方程是二元一次方程组的是( )