我国干湿地区划分的主要依据是：
A．降水量的多少
B．蒸发量的多少
C．降水量与蒸发量的对比关系
D．河流的多少
答案：C
题目分析：根据各地的干燥度（年内可能的蒸发量和多年平均降水量的比值），将中国划分为湿润地区、半湿润地区、半干旱地区和干旱地区．青藏高原以东，秦岭一淮河以南的亚热带和热带地区都是湿润地区．大兴安岭的北段的寒温带地区，也全是湿润地区．中温带、暖温带的东部山地，属于湿润地区；东北平原、华北平原和黄土高原的大部分地区，属于半湿润地区；贺兰山以东的内蒙古高原的大部分地区都是半干旱地区；我国的西北地区是干旱地区．
Every year there are hundreds of earthquakes in different parts of the world. In Sept.1923, Tokyo and Yokohama were both destroyed by an earthquake and the fires that followed it. They had to be completely rebuilt. One of the most serious earthquakes was in China’s Shanxi Province in 1556. It killed almost one million people. We measure an earthquake’s strength on the Richter scale. The Richter scale was introduced in 1935 in Southern California in the USA. It measures earthquakes on a scale of one to ten. Any earthquake measuring five or more is usually serious. The earth’s crust (地壳) is made up of layers of rock called plates. As these plates move, they sometimes crash against each other, causing the crust to quake. In cities such as Tokyo, where small quakes happen quite often, many modern buildings are designed to be flexible so when the earth moves, they move with it. Earthquakes can also break up gas or oil pipes. This can cause fires to break out, which can do as much damage as the earthquake itself. Another effect of earthquakes is tsunamis (海啸). These are huge waves created by earthquakes beneath the sea. They can be many meters high and cause great damage to coastal towns and cities. China, Japan, Russia and the USA have the highest occurrence (发生) of earthquakes in the world.
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