他们不得不拆掉那座危楼以确保行人安全。

They had to ___knock down the unsafe building to ensure pedestrian safety.

这家商店决定将家具价格大幅降低以清仓。

The shop decided to ___knock down the furniture prices for clearance.

那个足球运动员不小心把对方球员撞倒了。

The soccer player accidentally ___knocked down the opponent.