9个数复式二中二多少组怎么计算

简介：The main type of precipitation in China is frontal rain, which is formed when two airflows with different properties meet. In the spring in the south, as the temperature rises, the cold air from the north begins to weaken, and at this time the warm air from the southern Pacific Ocean begins to weaken. Moisture flows begin to strengthen, so cold and warm air stay in some places for a long time, forming precipitation.