[单项选择]贸易收支又称为( )。
A. 有形贸易收支
B. 无形贸易收支
C. 单方面转移
D. 多方面转移

The molecules of carbon dioxide in the Earth’s atmosphere affect the heat balance of the Earth by acting as a one-way screen. (1) these molecules allow radiation at visible wavelengths, where most of the energy of sunlight is concerned, to pass (2) , they absorb some of the longer-wave-length, infrared emissions radiated from the Earth’s surface, radiation that would (3) be transmitted back into space. For the Earth to maintain a constant average temperature, such emissions from the planet must (4) incoming solar radiation. If there were no carbon dioxide in the atmosphere, heat would (5) from the Earth much more easily.
Today, (6) , the potential problem is too much carbon dioxide. Could the increase in carbon dioxide (7) a global rise in average temperature, and could such a rise have serious (8) for human society Mathematical models that allow us to calculate the rise in temperature as a function of th
A. conquest
B. outcome
C. consequence
D. compromise.