sentences: animals require food to survive & a bear is a kind of animal ->  bears are a kind of animal that require food to survive  bears are a kind of animal that require food to survive & an animal will look for food in places that usually / sometimes contain food & a garbage can sometimes contains food ->  bears will learn to look in a garbage can for food to survive  bears will learn to look in a garbage can for food to survive & looking in a container sometimes requires opening that container -> bears will learn to open the garbage can to look for food