题目

A four-wheeled robot，known as Rover，has been tested by a team at Sydney University．It was used to move a herd of cows from a field to a dairy(牛奶场)． Researchers were amazed at how easily cows accepted the presence of the robot. They were not disturbed by it and the gathering process was calm and effective．Because the robot moved in a steady manner it allowed cows to move at their own speed，which was important in reducing injuries among cattle，said Dr Kendra Kerrisk，dairy researcher and associate professor． The robot was adapted from one that was already being use8．在夏天，人们喜欢吃“凉拌黄瓜”，盛黄瓜的盘子里原本没有水，但过一段时间后，盘子里有很多的水，这些水主要来自黄瓜细胞中的液泡结构，水能从黄瓜细胞内渗出细胞外，是因为黄花细胞的细胞液浓度小于（大于或小于或等于）外界溶液浓度．