单项选择题

The effect was temporary—temperatures started rising again after a year or so. But scientists began to wonder if the volcano hadn’t revealed a possible weapon against climate change. It takes only a back-of-the-envelope calculation to see that it would be possible to do artificially what the mountain did naturally. Ajudicious (明智的, 审慎的) application of sulfur dioxide (二氧化硫) to the upper atmosphere ,which could be accomplished by launching the gas from rockets, spraying it from high-altitude planes or releasing it from a big chimney, would have an almost immediate impact on temperature. And it would cost a thousand times less than even the most optimistic scenarios for cutting emissions. A small group of scientists began looking into how this kind of geo-engineering could be done most efficiently and with the fewest side effects.
Sulfur dioxide could be applied to the upper atmosphere in all the following ways EXCEPT

A. launching the gas from rockets.
B. releasing the gas from a big chirmley.
C. producing the gas from volcanoes.
D. spraying the gas from high-altitude planes.
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单项选择题
Botany, the study of plants, occupies a peculiar position in the history of human knowledge. We don’t know what our Stone Age ancestors knew about plants, but from what we can observe of preindustrial societies that still exist, a detailed learning of plants and their properties must be extremely ancient. This is logical. Plants are the basis of the food pyramid for all living things, even for other plants. They have always been enormously important to the welfare of people, not only for food, but also for clothing, weapons, tools, dyes, medicines, shelter, and many other purposes. Tribes living today in the jungle of the Amazon recognize hundreds of plants and know many properties of each. To them botany has no name and is probably not even recognized as a special branch of knowledge at all, Botany is the science that
A. studies existing tribes.
B. studies ancient way of living.
C. studies preindustrial societies.
D. studies plants.
单项选择题
They are giant geometric patterns, which appear over-night in a field of crops. Many people believe that they are made by aliens. Others call them hoaxes. Crop circle , as the mysterious patterns are called, became a hot phrase this month. A strange pattern 360 feet (110 meters) in diameter was discovered earlier this month in a wheat field in Oxfordshire, England. It’s believed to be the world’s first three-dimensional crop circle. The giant crop circle gives an impression of looking down on skyscrapers from above. The design’s discovery immediately generated a new tide of public interest in this mysterious phenomenon. Crop circles were first widely noticed in the late 1970s as many mysterious circles began appearing in crop fields throughout the English countryside. People were intrigued by these giant patterns. They were huge (at least tens of meters in diameters) and popped up over-night. No one knew how or by whom they were made. The world’s first three-dimensional crop circle appeared
A. in a wheat field in Oxfordshire.
B. throughout the countryside of Oxfordshire.
C. in the English countryside in the 1970s.
D. in all the wheat fields in the English countrysid
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