题目内容：
Scientists have been working hard to warn people________
参考答案：
答案解析：
单选题：Scientists have been working hard to warn people________
- 题目分类：综合类
- 题目类型：单选题
- 查看权限：VIP
请选择（50）处的最佳答案
请选择（50）处的最佳答案
Paragraph 2________
Paragraph 2________
请选择（5）处的最佳答案．
请选择（5）处的最佳答案．
Museums in the Modern World 1.Museums have changeD．They are
Museums in the Modern World 1.Museums have changeD．They are no longer places
The theme of the third paragraph is why the perennials, can
The theme of the third paragraph is why the perennials, can survive as plants fo