The moths tapped and blurred at the window screen.

窗帘上跳来跳去, 弄上了许多污点。

I used a throw rug to hide (or conceal ) the stain on the carpet.

我用小块地毯（或 conceal ) 将地毯上的污点遮盖起来。

The best way to get stains off collars is to use liquid detergent at full strength.

去除领子上的污点好的办法是使用未稀释的液体洗洁净。

There's a smear on your shirt.

你衬衫上有个污点。