From the passage we can infer that real happiness of life belongs to ______.

单项选择题On the basis of their models, scientists are of the opinion that______.

单项选择题A concentration of carbon dioxide in the atmosphere would______.

单项选择题Although the fuel consumption is greater in the northern hemisphere, temperatures there seem to be falling. This is ______.

单项选择题If the assumption about the delay of a new Ice Age is correct, _____.

单项选择题The article was written to explain______.