distractors: fast most best
sentence: It is well known of the   dangers   of a possible earthquake, and for centuries man has been making researches on earthquakes.More than 2,000 years ago,   for example  , a Chinese scientist named Zhang Heng   invented   a machine which could find out from which   direction   the seismic waves had come, and this machine is still   used   by scientists today.Now we know much more about earthquakes and   why   they happen, but we still cannot   tell   exactly when and where an earthquake will happen, and cannot   stop   it from happening.So earthquakes are among the   [MASK]   disasters in the world.