The meanings of It is very hard to

The meanings of It is very hard to imagine what life would be like without memory.everyday perceptions, the basis for the decisions we make, and the roots of our habits and skills are to be found in our past experiences, which are brought into the present by memory.Memory can be defined as the capacity to keep information available for later use. It not only includes ' remembering" things like arithmetic or historical facts, but also involves any change in the way an animal typically behaves. Memory is involved when a rat gives up eating grain because he has sifed (嗅出) something suspicious in the grain pilc.Memory exists not only in humans and animals but also in some physical objects and machines. Computers, for example, contain devices for storing data for later use. It is interesting to compare the memory storage capacity of a computer with that of a human being. The instant access memory of a large computer may hold up to 100,000 "words"一string of alphabetic or numerical characters一ready for instant use. An average U.S. teenager probably recognizes the meaning of about 100,000 words of English. However, this is but a fraction of the total amount of information that the teenager has stored. Consider, for example, the number of faces and places that the teenager can recognize on sight.The use of words is the basis of the advanced problem-solving intelligence of human beings. A large part of a person's memory is in terms of words and combinations of words. But while language greatly expands the number and the kind of things a person can remember, it also requires a huge memory capacity. It may well be this capacity that distinguishes humans,setting them apart from other animals.21 According to the passage, which of the following is TRUE about memory?A) It is based on the decisions we made in the past.B) It connects our past experiences with the present.C) It helps us perceive things happening around us every day.D) It is rooted in our past habits and skills.22. Memory is helpful in one's life in the following aspects EXCEPT that.A) it enables one to remember events that happened in the pastB) it warns people not to do things repeatedlyC) it involves a change in one's behaviorD) it keeps information for later use23. We can infer from the passage the author's view about computers and human beings in terms of intelligence is.A) computers can understand as many as 100,000 wordsB) computers have better memory than a child doesC) human beings are far smarter than computersD) computers are as intelligent as a teenager is24. What is the major characteristic of man's memory capacity according to the writer?A) It may change what has been stored in it.B) It may keep all the information in the past.C) It can remember all the combined words.D) It can be expanded by language.25. What sets humans apart from other animals?A) A far greater memory capacity.B) The ability to perceive danger.C) The ability to draw on past experiences.D) The ability to recognize faces and places on sight.