The devastation of Typhoon Morakot over Taiwan and eastern China is a reminder that the northwest Pacific is the most dangerous region in the world for tropical storms．The worst of these are typhoons, which are the same as hurricanes in the Atlantic and eastern Pacific, or cyclones in the Indian Ocean and Australia．They all have winds of more than 118km/h (73mph) spinning around a central core．
These storms start off as a mass of thunderstorms in the tropics outside the Equator．Given the right conditions, they form a bigger and more organised storm and feed off warm seas at more than 26．5C (80F) to get the fuel that they need to become a fully-fledged(羽毛丰满的) typhoon, hurricane or cyclone．Each storm is like a heat engine, extracting heat from the warm, humid air over the sea and turning it into phenomenal amounts of energy — equivalent to about 200 times the entire world’s electrical generating capacity．But warm, moist air is not enough — these storms also need slack winds aloft, because strong high-altitude winds can rip off the top of the storm clouds and send the entire storm tumbling（翻跟头）．
The damage from tropical storms often comes from their winds, or the storm surges from the sea as the winds pile up water into a huge battering ram(冲击夯) that floods coastlines．But the devastation from Typhoon Morakot came from its unbelievable rainfall — about a year’s average rain in some places — that set off landslides and mudslides．
45．According to the first paragraph, the common point among typhoons,hurricanes and cyclones is _______．
A．that they all come from the oceans
B．that they all have winds of over 118km/h spinning around a central core
C．that they all cause great damage
D．that they all can generate electricity
46．Which of the following is the best title of this passage?
A．Typhoon Morakat devestates Taiwan and eastern China
B．How is the typhoon formed?
C．Typhoon Morakot was how to devestate the areas it travelled
D．How terrible is Typhoon Morakat!
47．The devastation from Typhoon Morakot is mainly from ______．
A．its wind B．its rainfall
C．landslides and mudslides D．the storm
48．It can be inferred from the passage that ______．
A．Taiwan is off the northwest Pacific
B．the damage from tropical storms often comes from their winds
C．tropical storms often happen
D．tropical storms only need warm, moist air