汤山人
参考答案：
在南京市江宁县汤山镇，距今30-35万年。发现有头盖骨及牙齿等，南京人头盖骨顶部有一小块骨，称为“前心点小骨”，为南京人特有。
用适当的短语完成句子。
hear about, millions of, try doing sth. go around,
more than, send sb.(a) message(s), try to do sth.
1. I haven't seen Tom for a long time, so I ______ him ______ .
2. The earth is a planet and it ______ ______ the sun.
3. There has been life on earth for ______ years.
4. There is ______ one galaxy.
5. They have ______ send information to us.
6. —Tom, I've just heard that scientists have sent a spacecraft to Mars.
—Really?I haven't ______ this yet.
用二维表的形式来表示实体之间联系的数据模型叫做__________________。
