Answer：
China faces serious social and economic problems associated with overpopulation in the years to come. Overly populated regions lead to degradation of land and resources, pollution, and detrimental living conditions.
Answer: Sedimentary rocks make up 75 percent of the rocks at the earth's surface but only 5 percent of the outer 10 miles of the earth. Sediment, as distinguished from sedimentary rock, is a collective name for loose, solid particles and is generally derived from weathering and erosion of preexisting rock.
It could cause drought and famine I believe
The statement is correct.
When a flood is giving a time-bonding term, such as the 100-year flood, in this statement, it means that it has been noticed that the floods from the particular river occur on approximately that much of a time span.
If there has been a flood recently, than it most probably means that there isn't going to be a flooding caused by that river for the foreseeable future.
Now, there's always exceptions, as the climate patters are changing constantly, and there's always surprises, but in general, in lot of regions of the world, there has been noticed a certain consistency in some natural occurrences.
