Cloze-|||-Complete the passage with appropropriawords or expressions chosen from the box.-|||-Change the form when necessary.-|||-assess cooperate decefe emergency encounter-|||-explore negotiate reveal survive undertake-|||-at first figure out in sb.'s interest(s) size up within reach-|||-Animal behavior is the way that animals act.For example,how do-|||-they 1) to get food or take care of their young? How do they-|||-__-|||-2) __ an environment and keep themselves out of danger? How-|||-do they act when 3)) 9.enemies?Do they try to 4) __-|||-__-|||-the latter? How do they decide on fight or flight if deceiving does not work?-|||-Much of animal behavior is innate;that is,animals are born with it.However,-|||-research 5) __ that animals learn much other behavior.-|||-One simple type of learned behavior is habituation(习惯化).This happens-|||-when an animal learns to feel comfortable in a new situation and doesn't pay-|||-attention to it anymore.For example,young horses are 6) __-|||-_________________________afraid-|||-of noisy streets.But after a while,they learn to pay no attention to the normal-|||-sights and sounds of a city.-|||-Another kind of learned behavior is conditioniong(条件反射).It is a way of-|||-learning by association.In 1900,Ivan Pavlov,a Russian biologist,7) __-|||-____-|||-conditioning in dogs.Dogs innately salivate (分泌唾液)when they smell food.-|||-Pavlov 8) __ that if he rang a bell every time he gave food to a dog-|||-it would eventually salivate when it heard the bell alone,without food.-|||-The dog's senses were tricked,but most learning is 9) __-|||-animals.It enables them to better 10) __