— ______ is this shirt?
— It's ninety-nine yuan. ( )
A:How many
B:How much
C:How old
Lily is writing to her best friend ____ ____.
直线l1:y=k1x+b与直线l2:y=k2x在同一平面直角坐标系中的图象如图所示,则关于x的不等式k1x+b>k2x的解为( )
已知集合{x|ax+2=0}=∅,则a的值为____