A:have had; is running
B:had; is running
C:have; has been ru
D:have had; has been ru
用图象法解某二元一次方程组时,在同一直角坐标系中作出相应的两个一次函数的图象(如图所示),则所解的二元一次方程组是( )
在日常生活中,下列做法正确的是( )