stain|stained|stains

我意识到我的裤子上有一个污渍。

I realized that I had a ___stain on my trousers.

那果汁弄脏了我的衬衫。

That juice ___stained my shirt.

番茄酱会留下污渍——很难从衣服上洗掉。

Tomato sauce ___stains - it's really hard to get it out of clothes.