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Do scientists know how many cryptic species exist？
A．Not yet.
B．Yes, they do.
C．They will know the answer in another one or two years.
D．They will never know the answer.
答案
更多“Do scientists know how many cryptic species exist？A．Not yet.B．Yes, they do.C．They will kno”相关的问题
第1题
What do we learn about scientists in earlier times？
A．They claimed to know nothing about nature.
B．They believed in results from scientific observation.
C．They paid much attention to the problems they didn't understand.
D．They invented false theories to explain things they didn't understand.
第2题
Do scientists know how many cryptic species exist？
A．Not yet．
B．Yes．they do．
C．They will know the answer in another one or two years．
D．They will never know the answer．
第3题
What do we learn about David Bradley？
A．He is one of the scientists who "should know better".
B．He has made many experiments on antioxidants.
C．He is against taking extra antioxidants.
D．He is against taking extra vitamins.
第4题
Why do the scientists want to do the study？ 查看材料
A.They want to make sure if chocolate is really beneficial.
B.They want to see how chocolate improve health.
C.They want to know why people love to eat chocolate.
D.They want to find out the benefits of pure flavanols.
第5题
A．theories of its origin and history are varied
B．our knowledge of it is highly insecure
C．only a very small sample of it has been observed
D．few scientists are involved in the study of astronomy
第6题
Land is becoming desert little by little because ______.
A．plants can't grow there
B．there is not enough rain
C．people haven't done what scientists wish them to do
D．scientists know little about the deserts
第7题
A. seem to know how to control laughter B. reduce your blood pressure
C. why people laugh
D. the intake and release of air
E. the purpose of laughter is to reduce stress
F. the way it affects the immune system
Scientists do not have clear evidence as to______
第8题
听力原文： Man has a big brain. He can think and speak. Scientists used to think that men are different from animals because they can think and learn. They now know that animals can learn —dogs, rats, birds —and worms —can learn. So scientists are beginning to understand that men are different from animals because they can speak. Animals cannot speak. They make noises when they are afraid, or angry, or unhappy. Apes are our nearest cousins. They can understand some things more quickly than human beings, and one or two have learned a few words. But they are still different from us. They cannot join words and make sentences. They cannot think like us because they have no language. They can never think about the past or the future.Language is a wonderful thing. Man has been able to develop civilization because he has language. Every child can speak his own language very well when he is four or five —but no animal learns to speak. How do children learn？ Scientists do not really know. What happens when we speak？ Scientists do not know. They only know that man can speak because he has a big brain.
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A．Because he has a big brain.
B．Because he learns to speak.
C．Because he develops civilization.
D．Because he knows many words.
第9题
In the author's opinion, why do more people in Britain oppose animal experiments？
A．Because they are kinder than those in the United States.
B．Because they don't know the benefits resulting from animal tests.
C．Because most of the medicines don't need animal experiments to work well.
D．Because some scientists use rare species for their medical experimentation.
第10题
What do we know about the Student Leadership Meeting？
A．It was first held in 2004.
B．It is held every three years.
C．lt provides free meals for students.
D．It invites students from Manhattan.
