46. Which is the main idea of the passage?
(A) The exhaustion of natural resources over the years.
(B) Why Taiwan is such a dangerous place to live.
(C) The dangers of natural disasters and the fight against them.
(D) How people dealt with natural disasters in ancient times.

前半段是講災難的種類及造成的影響，後半段是講人們對天災的應對和處理，所以最接近的答案選(C)

• People once thought that a solar eclipse(日蝕) meant that a terrible disaster would happen.
• Now we know that is not true, but millions of people do suffer from true natural disasters ranging from deadly typhoons from the sea to tornadoes on land.
• Fossils(化石) show that natural disasters have been affecting life on earth since long before human existed. 
• These disasters still affect us all. 
• Our oceans and straits may be affected by typhoons.
• In the mountains and gorges(峽谷) of Taiwan and elsewhere, the rains brought by these storms often lead to mudslides.
• In other parts of the world, there is sometimes not enough rain, resulting in a drought(旱災).
• Because of the drought, crops wither(枯萎) and people starve(挨餓). Earthquakes are also a constant danger.
• Even a small tremor(小地震) is able to destroy a poorly constructed building or the span of a bridge.
• Larger earthquakes sometimes cause huge waves, called tsunamis(海嘯), which destroy villages and kill thousands of people. The eruption of volcanoes can also be a major hazard and the vapors that spill from them can be as dangerous as the mud and ash that come from them. 
• Governments around the world spend large amounts of money on efforts to protect their people from the effects of natural disasters and the famines(饑荒) that often follow.
• After a disaster strikes, governments and individual donors from around the world rush to help those nations that have been affected, rebuilding farms and canals(運河).
• Many governments work through the United Nations to develop systems to warn people of tempests(風暴) and tsunamis approaching the coast.
• Despite our great advances in science and technology, we still suffer from natural disasters the same way that our ancestors(祖先) did thousands of years ago.