A: 倾倒液体
B: 量取液体
C: 点燃酒精灯
D: 加热液体
(-1)4的相反数是( )
在直角坐标系xOy中,已知点A(4,2)和B(0,b)满足|BO|=|BA|,那么b的值为( )
Maybe your brother forgot to turn off the light when he left the room.