—Well, it's a little far from here. What about ______ shared bikes?
A:to walk; to ride
B:to walk; riding
C:walk; to ride
D:walk; riding
已知关于x的方程(a-1)x2-2x+1=0有实数根,则a的取值范围是( )
我们的生活中处处有低碳,你低碳了吗?图中属于低碳行为的是( )
人类的生存____于环境。