下列各式中,属于二元一次方程的是( )
A:x2+y=0
B:x=2y+1
C:x+y3-2y=1
D:y+12x
在验证“电功与电流、电压的关系”活动中,同学们设计了如图甲、乙、丙三个电路.
The box was heavy but he to carry it.
亚洲分布范围最广的气候类型是