题目

小明将倒入水中的土壤进行搅拌，并静置一段时间，观察到土壤沉积物有分层情况。实验中，为什么要将搅拌后的混合物静置一段时间？合理的解释是（ ）。 A . 让土壤充分地溶解在水中 B . 让水分充分地从土壤中分离出来 C . 让混合物充分地沉淀下来 D . 小明需要更充分的时间进行观察 答案：C把下列短文抄写在方框内 Mt. Qomolangma was first conquered (征服)in 1953, when Sir Edmund Hillary and Sherpa Tenzing, his guide, became the climbers to reach the top. More than 750 times have people tried to conquer the mountain, but not all successful, yet every climber knows the dangers. This doesn’t stop teams of climbers arriving at the base camp every year with the courage of reaching the top. 　 Two such climbers, and two unlucky ones are Scott Fischer and Rob Hall. Fischer, an American guide with much experience, was lost in a terrible storm which swept across the mountain. A rescue team found him and his friend, but didn't manage to bring Fischer to safety in the terrible conditions because he was dying. New Zealander RobHall, another experienced climber and guide, was lost near the top. These two men had something in common: they were both guides and always took a "tour" of less experienced climbers up the mountain.