21、 阅读材料，回答21-40题。
Today anyone will accept money in exchange for goods and services.. People use money tobuy food, furniture, books, bicycles and hundreds of others they need or want. When they work,they usually get paid in money.
Most of the money today is made of metal or paper. But people used to use all kinds of things as money. One of the first kinds of money was shells.
Shells were not the only things used as money. In China, cloth and knives were used. In thePhilippine Islands, rice was used as money. In some parts of Africa, cattle were one of the earliestkinds of money. Other animals were used as money, too.
The f'irst metal coins were made in China. They were round and had a square hole in the cen-tre. People strung them together and carried them from place to place.
Different countries have used different metals and designs for their money. The first coins inEngland were made of tin. Sweden and Russia used copper to make their money. Later, othercountries began to make coins of gold and silver.
But even gold and silver were inconvenient if you had to buy something expensive. Again the 'Chinese thought of a way to improve money. They began to use paper money. The first papermoney looked more like a note from one person to another than paper money used today.
Money has had an interesting history from the days of sh~ll money until today.
Which of the following can be cited as an example of the use of money in exchange for services?
A．To sell a bicycle for $ 20.
B．To get some money for old books at a garage sale.
C．To buy things you need or want.
D．To get paid for your work.


22、 Where were shells used as money in history?
A．In the Philippines.
B．In China.
C．In Africa.
D．We don' t know.


23、 Why, according to the passage, did ancient Chinese coins have a square hole in the centre?
A．Because it would be easier to put them together and carry them around.
B．Because it would be lighter for people to carry them from place to place.
C．Because people wanted to make it look nicer.
D．Because people wanted to save the expensive metal they were made from.


24、 Why does the author say that even gold and silver were inconvenient if you had to buy some-thing expensive?
A．Because they are easy to steal.
B．Because they are difficult for people to obtain.
C．Because they are not easy to carry around.
D．Because they themselves are expensive, too.


25、 Which do you choose as the best title for this passage?
A．Money and Its Uses
B．Different Things Used as Money
C．Different Countries, Different Money
D．The History of Money


26、 阅读材料，回答26-45题。
It is difficult to imagine what life would be like without memory. The meanings of thousarof everyday perceptions, the bases for the decisions we make, and the roots of our habits and skiare 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 inclucnot only "remembering" things like arithmetic or historical facts, but also involving any change the way an animal typically behaves. Memory is involved when a rat gives up eating grain becathe has sniffed something suspicious in the grain pile. Memory is also involved when a six-year-(child learns to swing a baseball bat. Memory exists not only in humans and animals but also in some physical objects and nchines. Computers, for example, contain devices for storing data for later use. It is interesting compare the memory-storage capacity of a computer with that of a human being. The instant-accmemory of a large computer may hold up to 100,000 "words"--ready for instant use. An aver U.S. teenager probably recognizes the meaning of about 100,000 words of English. However, is but a fraction of the total amount of information which the teenager has stored. Consider, for ample, 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 bein
A large part of a person' s memory is in terms of words and combinations of words.
According to the passage, memory is considered to be__________
A．the basis for decision making and problem solving
B．an ability to store experiences for future use
C．an intelligence typically possessed by human beings
D．the data mainly consisting of words and combinations of words


27、 The comparison made between the memory capacity of a large computer and that of a human being shows that__________
A．the computer' s memory has a little bigger capacity than a teenager' s
B．the computer' s memory capacity is much smaller that an adult human being; s
C．the computer' s memory capacity is much smaller even than a teenager' s
D．both A and B


28、 The whole passage implies that__________
A．only human beings have problem-solving intelligence
B．a person' s memory is different from a computer' s in every respect
C．animals are able to solve only very simple problems
D．animals solve problems by instincts rather than intelligence


29、 The phrase "in terms of" in the last sentence can best be replaced by__________
A．"in connection with"
B．"expressed by"
C．"consisting"
D．"by means of"


30、 20. The topic of the passage is:__________
A．What would life be like without memory?
B．Memory is of vital importance to life.
C．How is a person' s memory different from an animal' s or a computer' s? "
D．What is contained in memory?