如图所示，用水平外力F将木块压在竖直墙面上，木块保持静止，下列说法中正确的是（ ）
A．木块所受的重力与墙对木块的静摩擦力是一对平衡力
B．木块所受的重力与墙对木块的静摩擦力是一对作用力与反作用力
C．木块对墙的压力与水平外力F是一对平衡力
D．水平外力F与墙对木块的支持力是一对作用力与反作用力
A、木块处于静止，在竖直方向上受两个力，即重力和墙对木块的静摩擦力．两个力是一对平衡力．故A正确，B错误．
C、木块在水平方向上受外力F和墙对木块的支持力，两个力是一对平衡力．故C、D错误．
故选A．
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