题目

如果你家里的食用花生油混有水份，你将采用下列何种方法分离（    ） A、过滤             B、蒸馏           C、分液           D、萃取 答案：C阅读理解 　　A team of scientists proved that seals (海豹) had a very good sense of heating. These men trained blind seals to expect food when they heard sounds. The seals always began snapping (猛咬) when a strong signal was sounded. 　　It was proved that even a soft signal, a considerable distance (相当远的距离) away, could make these sea animals respond (起反应). That should make the fisherman who makes much noise while working, or talks loudly, start thinking. 　　The same team of scientists also trained seals to recognize different sounds. One bell-tone meant food, two bell-tones meant no food. In the beginning, the seals made mistakes when the two-bell tones were sounded. They were given a light tap after each mistake. The seals were good learners. They easily learned to tell the difference between the sounds. 1．Why was it necessary to use blind seals? [　　] A．were unable to use sight for clues (线索) B．had better hearing C．were waiting to be fed D．were the only animals to be found 2．To those seals strong signal meant ________. [　　] A．snappingB．nothing C．foodD．a light tap 3．The article doesn't say directly but suggests that fishermen usually think ________. [　　] A．seals have no sense of hearing B．seals have good sense of hearing C．seals can only recognize bell sounds D．seals can not hear soft and long distant sounds 4．Light taps were given to those who ________. [　　] A．expected food B．came for food C．made mistakes D．recognized the sounds