A:A+B=C+D
B:2A+B=2C+D
C:2A+B=C+2D
D:A+2B=2C+D
— It's dangerous to swim here. Look at the sign.
— Oh, I notice it. Thanks for telling me.
下列物质不能发生银镜反应的是( )
若 a<b ,则下列各式一定成立的是( )