20．Maybe you know floods（洪水），droughts（干旱），earthquakes，sandstorms and so on．But have you ever heard of typhoons？
Typhoons are some of the worst storms，usually around the Pacific Ocean and the South China Sea．Most happen in July，August and September．
How does a typhoon happen？When lots of sea water gets hot in the summer sun，it evaporates（蒸发掉） into the air．This makes the air hotter．When the air gets warm enough，it starts to move higher up into the sky．Then，cooler air around it rushes in． It fills the space that is left．After the air gets warmer，it starts to move quickly，making wind．The wind goes in circles，and it keeps moving higher in the sky．The warmer the air gets，the quicker the wind moves．And when the wind moves faster than 30 meters a second，a typhoon begins．
A typhoon has two parts．One is called the"eye"．In the eye，the wind does not move so fast．The other part is the wall of clouds around the eye．This is where the strongest wind and hardest rains are．
Typhoons are very dangerous．In 2004，Typhoon Yunna killed 164 people in Zhejiang，and 24 people were missing．In May 2006，Typhoon Pearl hit Guangdong and Fujian，and thousands of houses were damaged．
What to do when a typhoon hits
Stay inside．Close all the windows and stay away from them．
Try to bring all of your things inside．Strong winds could even blow away your bikes!
Listen to the radio or TV for important information．
If you're told to go to a safer place，do so right away．
31．Typhoons often happenA．
A．in the hot season
B．in the cold season
C．in the daytime
D．at night
32．Which picture can tell the meaning of the underlined sentences"…，it starts to move higher up into the sky．Then，cooler air around it rushes in．"？B
33．When a typhoon comes，we CANNOTC
A．close all the windows
B．listen to typhoon news
C．stay outside with our bikes
D．stay inside the strong house
34．This passage is mainly about．A
A．the knowledge of typhoon
B．the eye of a typhoon
C．the most dangerous typhoon Yunna
D．the names of typhoon
35．Which of the following is TRUE ac cording to the passage？D
A．The warmer the air gets，the slower the wind moves．
B．This year Typhoon Peal killed 164 people in Zhejiang．
C．The strongest winds and harder rains are in the eye of typhoon．
D．A typhoon will happen when the wind goes faster than 30 meters a second．
