Questions 6 to 10 are based on the followingpassage: It is difficult to imagine what life would belike without memory. (78) The meanings of thou-sands of everydayperceptions, the bases for the decisions we make, and the roots of our habitsand skills are to be found in our past experiences，which are brought into thepresent by memory. Memory can be defined as the capacity to keepinformation available for later use. It includes not only “remembering” thingslike arithmetic or historical facts, but also involving any change in the wayan animal typically behaves. (79) Memory is involved when a rat gives upeating grain be-cause he has sniffed something suspicious in the grain pile. Memoryis also involved when a six- year-old child learns to swing a baseball bat. Memory exists not only in humans and animalsbut also in some physical objects and ma-chines. Computers, for example,contain devices for storing data for later use. It is interesting to comparethe memory-storage capacity of a computer with that of a human being. Theinstant-access memory of a large computer may hold up to 100,000 “words”一ready for instant use. An averageU. S.teenagerprobably recognizes the meaning of about 100,000 words of English. However,this is but a fraction of the total amount of information which the teenagerhas stored. Consider, for ex-ample ，the number of faces and places that the teenager can recognize on sight. The use of words is the basis of the advancedproblem-solving intelligence of human beings. A large part of a person’s memoryis in terms of words and combinations of words. 6. Accordingto the passage, memory is considered to be_____________.