���˸߿�

46、 Generally speaking, a man can tell __ different odors.
A． five million
B． more than 10,000
C． fewer than 10,000
D． no more than 10,000

47、 The best title of the passage is“ __ ”.
A． The Human Sense of Smell
B． Dogs Have Poor Eyesight
C． Sense of Smell
D． Dogs Have Excellent Sense of Smell

48、 Why is the program that's trying to save condors putting them into danger?
A． They have captured all the condor
B． Birds raised in captivity are attracted to human
C． Hunters want to shoot the
D． There is not enough food for condor

49、 What is one suggestion to help save the condors?
A． Let all condors fre
B． Don't allow anyone to hun
C． Make hunters use different kinds of bullet
D． Move the condors out of Californi

50、根据以下资料，回答50-69题。 　　The California condor is the largest bird in North America．It is an endangered species．20 years ago there were less than 30 birds left．All of the birds were trapped and kept in safe places．The number of condors grew larger．Puppets that looked like condors were used to take care of babies so that more eggs could be hatched.
　　In the last few years, some of the condors have been returned to the wild．But they seem to like humans now and come into danger around people．Some birds perch on houses and tear up roofs．Some have even gone into houses．Birds have been shot, poisoned, and killed by power lines．
　　Now there is another problem．Condors find dead animals that hunters have killed．The bullets cause lead to get into the meat and it can kill the condors．Some people think hunters should use different bullets．Other people think that the birds should not be put into the wild. Why is lead poisoning a new problem for condors?
A． Hunters shoot condor
B． Puppet rearing practices have caused i
C． Hunter's bullets contain lead which poisons the meat condors ea
D． They never used to like lea

51、 If the condor population has tripled since two decades ago, about how many are there now?
A． 90．
B． 60．
C． 33．
D． 300.

52、 The main factor in changing the amount of heat on the earth is __.
A． man's agriculture and industry ways
B． natural weather
C． wind and rain
D． clouds

53、 The warming weather of the past hundred years may __.
A． begin
B． end
C． be another ice age
D． start

54、根据以下资料，回答54-73题。 　　It is possible that the weather of the world may be changing．Some scientists imagine that this could even mean the beginning of another ice age．The effects of such a change in weather on human population of the world would be frightening.
　　Recent research suggests that the warming trend (倾向 ) of the past hundred years or so may be coming to an end．During the past ten years, scientists tell us that the temperature of the world has dropped a little．This would have effects on wind and rain in the weather picture.
　　Scientists believe clouds may be an important factor (因素) in changing the amount of heat on the earth．Another possibility is that man's agriculture and industry ways may affect the natural weather. The weather of the world seems to be getting __.
A． hotter
B． colder
C． warmer
D． freezing

55、 The temperature of the world in the past ten years has dropped a little __.
A． because wind and rain changed the weather
B． which would have effects on wind and rain
C． because wind and rain did not change the weather
D． which would not have effects on wind and rain