19．21．Water is called liquid gold because it'svery precious and water resources are limited．
22．There'splenty of salty water in the sea，but we can neither drink nor take a shower with it．
23．Floods are powerful and harmful and they can causehuge damage in economy．
24．People whosuffer from an earthquake or a flood may have nowhere to live．
25．People donate （捐贈）．money，food，water and medicine tothe homeless through the Red Cross．
分析 略
解答 21．very precious 22．plenty of 23．huge damage 24．suffer from
25．the homeless
點評 略
