You can't have a situation where enemy nationals barge into your country, tear up the border fence and try to infiltrate.

你肯定不会允许敌对国家的国民闯入你的国家，撕破栅栏，试图潜入。

Love your neighbor, but don't tear down your fence.

可以友爱你的邻居，但不用拆下你的篱笆。

Sometimes they would lob rocks over the high fence around the hothouse, and occasionally they would tear through the overhead net and he'd have to replace panes.

有时他们把石头扔过温室周围的高大围栏，石块偶尔会撕开上面的天棚，他不得不替换它们。