他们已经拆掉了那家老电影院。

They've ___knocked the old movie theater ___down.

我们应该让人把这些空置的办公楼拆掉，改建成公园。

We should have the empty office buildings ___knocked ___down and replaced with parks.

为了公共安全，市政府决定拆除那座危险的建筑。

The city decided to ___knock that dangerous structure ___down for public safety.