A. Atmospheric Scientists
B. The Calculations Made at the Berlin Workshop
C. The Previous Calculations of the Effect of Aerosols
D. The Scientists’ Agreement
E. The Authoritative Conclusion
F. Greenhouse Gases
Paragraph 4 ______

单项选择题Ocean exploration is not so expensive as space travel mainly because ().

A. it is not affected Earth’s gravity
B. most undersea vehicles operate at the end of long ropes
C. ROVs have been put to use
D. there is no need for submersibles to get away from Earth’ s gravity

单项选择题In aboutl5 years’ time from now , robots ______.

填空题Paragraph 3 ______

单项选择题The reason why the “old rich” look down upon the “new rich” is that______.

单项选择题Among humanity’s current problems, the chief concern of the scientists is the reduction of biological diversity.()

A. Right
B. Wrong
C. Not mentioned