Cloze 2. Theme-relatedRead the passage carefully until you have got its main idea, and then select one appropriate word foreach gap from the box following the passage.Behavior is the way that animals act. For example, how do they get food or take care of their young? How do they find a place to live in or _________(1) themselves from danger ! Much behavior is innate; that is, animals are born with it. ___________ (2),animals learn much other behavior. There are several kinds of learned behavior.One simple___________(3) of learned behavior is habituation. This happens when an animal learns to feel comfortable in a new __________(4) and doesn't pay attention to it anymore. For example, young horses are often afraid of noisy streets. But after a while, they learn to pay no attention to the normal____________(5)and sounds of a city.Another kind of learned behavior is conditioning. It is a way of learning by association——that is, by putting _________(6)different ideas. In 1900, Ivan Pavlov, a Russian biologist, studied conditioning in dogs. Dogs innately salivate (produce liquid in the mouth) when they smell food. Pavlov_______________(7) a bell every time he gave food to a dog. Soon the dog started to____________(8)the sound of the bell with the smell of food. After some time, it salivated when it heard a bell alone,_________________(9) food.Learning is important for all animals in a new _______________(10).It allows an animal to be adaptable—that is, able to change in a new situation.