填空题 ● The ocean is still salty.
◇ Evaporated water leaves 1 behind, which makes the ocean salty.
● How did oceans form?
◇ It is said that oceans formed at least 2 ago.
◇ Atmosphere and clouds on the Earth are gasses, such as 3 escaping from the planet"s interior.
● Were oceans in the past as salty as they are today?
◇ Oceans were not so salty in 4 state.
◇ With 5 sweeping over the planet"s 6 and filtering down to the hollows, materials containing ingredients of salt were picked up.
◇ Chlorine, came from the 7 and gaseous fallout of land and 8 volcanoes.
◇ The oceans" salt content increases because of the steady flow of 9 and streams and the 10 of volcanoes and undersea vents.