In Australia, there are some poor penguins. Because of sea pollution (污染), they have toxic (有毒的) oil on their feathers. The oil can harm their feathers. This way, their feathers can not keep them warm. Penguins may also eat the oil. To save these penguins, people knit (织) sweaters for them. The sweaters keep the penguins warm. They also stop penguins from eating the oil.