—What's the man ___?
—I don't know. [ ]
A. talking
B. waiting
C. taking
D. listening
答案:C
妈妈买了4千克香蕉和3.5千克苹果,一共花了51.2元.已知香蕉每千克7.2元,苹果每千克多少元?
在测量平面直角坐标系中,横轴为( )。
A.X轴,向北为正
B.Y轴,向东为正
C.X轴,向东为正
D.Y轴,向北为正