题目

500 dog owners played the same games at hone that researchers use in the laboratory and contributed data to a study of what goes on inside the minds of their dogs. In one of the game-like tests, the dogs watched as their owner hid food under one of two cups. Then while the dog'。eves were covered, the owner switched the food to the other cup. And the owners found that most dogs went to where they last saw the food. The result has been repeated in seven different research groups and more than a dozen different studies. Most people think dogs use their sense of smell for everything, a r体积为1m3的冰块，它的质量是________kg，全部熔化成水后，水的质量是________kg，水的体积是________m3，它的密度变为________．（冰的密度为0.9×103 kg/m3）