关于美国经济的描述，错误的是（      ）    

阅读理解。根据短文内容，选择正确答案。

    A lot of boys and girls in west countries are wearing the same kinds of clothes: Many of them have long hair, so it is often difficult to tell whether they ate boys or girls.

    One day, an old man went for a walk in Washington. When he was tired he sat down on a long chair. A young person was standing onthe other side of the pool.

  “Good Heavens!” the old man said to the person who was sitting next to him on the chair. “Do you see that person with long hair? Is ita boy or a girl?”

  “A girl.” said his neighbor, “She's my daughter.”

  “Oh!” the old man said quickly, “I'm sorry. I didn’tknow that you were her mother.”

  “I'm not,” said his neighbor, “I'm her father.”

为了研究物质的某种特性，某同学测得四组数据，填在下表中：

（1）将上表填写完整．

（2）比较1、2两次实验数据，可得出结论：同一种物质，它的质量跟它的体积成____ ．

（3）从表格中发现：同种物质组成的不同物体，质量与体积的比值____ ，不种物质组成的不同物体，质量与体积的比值一般____