阅读第一篇underground water 中的第四题,完全找不到答案的解题依据嘛,望高人解答!谢谢~
Paragraph 2: The necessary space isthere, however, in many forms. The commonest spaces are those among theparticles—sand grains and tiny pebbles—of loose, unconsolidated sand and gravel.Beds of this material, out of sightbeneath the soil, are common. They are found wherever fast rivers carryingloads of coarse sediment once flowed. For example, as the great ice sheets thatcovered North America during the last ice agesteadily melted away, huge volumes of water flowed from them. The water wasalways laden with pebbles, gravel, and sand, known as glacial outwash, that was deposited as theflow slowed down.
4. According to paragraph 2, where isgroundwater usually found?
○Inside piecesof sand and gravel
○On top ofbeds of rock
○In fastrivers that are flowing beneath the soil
○In spacesbetween pieces of sediment