sandstorms are among nature's most violent and unpredictable phenomena(现象)．high winds lift sand into the air，reducing visibility(能见度) to almost nothing in a few seconds.nearly all dust storms are capable of causing property damage，injuries，and deaths.no matter where you live，it's a good idea to know what to do if you see a wall of sand racing toward you.here are some tips for you. be prepared.if you are in a stormy area，carry a
