A:3.5
B:4
C:7
D:14
The students carried their books away from the school ____ ____ .
如图所示,A、B为完全相同的两个容器,分别盛有7cm、5cm深的水,A、B之间用导管连接.若将阀门K打开,最后A、B两容器底部受到水的压强之比为( )