drop holes造句

• The underground water flows a few meters and enters a water - dropping hole of the underground river . when the water level rises one to two meters high , it promptly drops down , producing thunder - like drainage sound
  原来，虹吸泉所在地是奇风洞地区的最低点，二者相通，地下河水流淌数米后，进入暗河的一个落水洞，当水位升高一至二米后会猛然跌落。