题目内容
（请给出正确答案）
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.
简答题官方参考答案
（由简答题聘请的专业题库老师提供的解答）
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
A．The scientists know it is definitely getting smaller.
B．The scientists know it is near extinct.
C．The scientists still do not know.
D．The scientists think it is rebounding slightly.
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.
A．Some researchers have told them
B．Many women say so
C．They know it by experimenting on rats
D．They know it through their own experience
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.
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
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.
A、They are much larger than other stars.
B、They exert a force of gravity on other stars.
C、They are visible with special telescopes.
D、It is possible to calculate their mass and energy.
Land is becoming desert little by little because ______.
A．plants can't grow there
B．there is not enough rain
C．people haven't clone what scientists wish them to do
D．scientists know little about the deserts
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.
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______
警告：系统检测到您的账号存在安全风险
为了保护您的账号安全，请在“简答题”公众号进行验证，点击“官网服务”-“账号验证”后输入验证码“”完成验证，验证成功后方可继续查看答案！
