Don't leave rubbish, please.

请不要乱扔垃圾。

They tell people not to leave rubbish.

他们告诉人们不要丢垃圾。

We shouldn't leave rubbish here and there.

我们不应该在这里和那里留下垃圾。

We shouldn't leave rubbish here and there.

我们不应该把垃圾扔在这里和那里。

People cut down too many trees and leave rubbish everywhere.

人们砍伐很多的树木、到处乱扔垃圾。