51、根据以下内容回答51-70题：
A tid．al wave is a very large and very destructive wall of water that rushes in from the ocean toward the shore．Many scientists call these huge waves tsunami(海啸)．In Japanese tsunami means“storm wave”0r“tide”．But do you know that tidal waves are not caused bv storms and that they are not true tides at all?A true tide is the regular rise and fall of ocean waters，at def-inite times each day．But a tidal wave comes rushing in suddenly and unexpectedly．A tidal wave is caused by an underwater earthquake．Scientists call the underwater earthquake a seaquake．The word“seaquake”is made up of two words．the word’“sea”which means“ocean”and the word“quake”．To quake means“to shake”or“to tremble”．When a seaquake takes place at the bottom of the ocean，the ocean floor shakes and trembles，and sometimes the ocean floor shifts．It is this shifting that produces the tidal wave．The tidal wave begins to move across the sea at great speed．
Tidal waves have taken many human lives in the past．Today scientists can predict when a tidal wave will hit land．They use a seismograph to do this．A seismograph is an instrument that records the strength，the direction，and the length of time of an earthquake or seaquake．It is not possible to hold back a tidal wave，but it is possible to warn people that a tidal wave is coming．This warning can save many lives．
According to the article，what causes a tidal wave?
A．The rise and fall of ocean water at regular times．
B．Seaquakes．
C．Storm．
D．The great speed of the ocean waves．


52、What do we know about tsunami?
A．It is a scientific term for seaquakes．
B．It iS a Japanese name for true tides．
C．It is an African word for hurricanes．
D．It is a name of an unknown American scientist．


53、According to the article，which of the following is NOT true?
A．Scientists can predict when seaquake will hit land．
B．Seismograph is used to predict when a tidal wave will hit land．
C．Holding back a tidal wave is out of the question．
D．True tides rise and fall regularly．


54、According to the passage，what is the difference between tidal waves and tides?
A．Tidal waves are caused by underwater earthquake，but tides are not．
B．Tidal waves have regular rise and fall，but tides have not．
C．Tidal waves can be prevented，but tides can not．
D．Tidal waves can hit the land，but tides can not．


55、It can be inferred from the passage that__________ ．
A．tidal waves used to kill more people in the past
B．tidal waves used to be more powerful than storms before
C．neither tides nor tidal waves can be predicted
D．tidal Waves are hotter than tides

56、根据以下内容回答56-75题：
“There is no arguing about taste”一runs the Latin proverb．But taste did not just hap—pen．Cuhural，historical，biological and environmental events have interacted to cause frogs，for example，to be viewed as delicious in southem China but to be regarded with revulsion(厌恶)in northern China．Even though much remains unknown，tastes cannot be dismissed as in．arguable or illogical；an attempt will be made here to discover why，as Lucretius put it，“What is food to one man may be fierce poison to others?”
Among the approximately thirty million tribal people of India，a total of 250 animal species are avoided by one group or another．Most of these people will not eat meat from a tiger or any of various snakes．Although they say they feel a relationship with these animals，it is obvious that both are highly dangerous and that hunting them systematically would be foolish．
Monkeys are avoided，probably because they look like human beings in appearance；in these tribes，man-eating is viewed as extremely cruel．A reluctance to eat some female animals has been attributed to respect for the mother's role，but it could also be due to a policy of allo-wing the females to reproduce and provide more young for people．Many tribes avoid eating any animal that has died of unknown causes all intelligent attitude in view of the possibility that the animal might have died from a disease that could spread to humans．Animals that consume gar-bage are similarly avoided，an adaptive step that prevents contact with parasites(寄生虫)，and that might explain why members of one tribe eat any of twenty-one different species of rats，but not the house rats．
“There is no arguing about taste”，which means __________.
A．people don’t like to talk about food
B．one’s taste in food is hard to explain
C．there is no quarrelling about to eat
D．no arguments about taste have been heard of before


57、It can be concluded from the first paragraph．that__________ ．
A．the author is against eating frogs
B．taste is illogical and inarguable
C．some types of frogs are poisonous
D．taste is influenced by many factors


58、The tribal people in India don’t eat snakes because__________ ．
A．they are very dangerous
B．they are respected by Indians
C．they may spread disease
D．they help kill rats


59、The tribal people in India may not eat the following animals EXCEPT__________ ．
A．donkeys
B．tigers
C．female deer
D．house rats


60、The passage is probably written for the purpose of__________ ．
A．introducing the eating habit of Indian tribal people
B．distinguishing different types of taste．
C．accounting for people’s different choices of taste
D．explaining the relationship between taste and tribes