[填空题]
A tsunami of wavelength 250 km *zi y 67tzfrsowa1 llk2):rhp+hb e.7and. n:9reni3f:0odbqu q velocity 750 km/h travels across the Pacific Ocean. As it approaches Hawaii, people observe an unusual decrease of sea level in the harbors. Approximately how much time do 9nn3 0frd i. :qebqo:uthey have to run to safety? (In the absence of knowledge and warning, people have died during tsunamis, some of them attracted to the shore to see stranded fishes and boats.) min
