第16题: [单项选择]Thousands of years ago people were forced to leave their homeland because ______. A. the earth was in an ice age B. they found their homeland getting colder C. huge sheets of ice were spreading over the land D. they had to stay near the animals they hunted for food 参考答案:D 答案解析:第三段第三、四句话说到,因为巨大的冰层覆盖着大陆,所以供猎食用的动物被迫迁徙,于是以此为生的人类也不得不搬迁或靠近动物居住。