依次填入下列横线处的词语，最恰当的一组是（）。

①2003年2月1日，美国“哥伦比亚”号航天飞机在从太空返回地面途中解体，机上7名宇航员全部______。消息传出，世界震惊。

②地球生态系统是经过自然界的长期______形成的，它是人类生活的惟一基础，失去这一基础，人类只能彻底毁灭。

③现在提倡的“研究性学习”模式，就是让我们置于问题情景中去体验，去动手、动脑，感受_______方案的设计、现象的观察、数据的处理和结果的分析。

A．遇害；变化；实验

B．遇难；演化；实验

C．遇难；演化；试验

D．遇害；变化；试验

在改写后的句子中填入所缺单词，使其与原句意思相符：

1. The boy is five years old. He couldn't find his way in the park yesterday.

    The _______ boy _______ _______ _______ in the park yesterday.

2. How often does Jim get a letter from his parents?

    How often _______ Jim _______ _______ his parents?

3. The fire burned Wang Fang's neck, arms and face.

    Wang Fang _______ her neck ,arms and face in the _______.

4. This is Millie's blanket.

    This blanket _______ _______ Millie.

5. They may visit a home for the elderly this Sunday.

    _______ they _______ _______ a home for the elderly this Sunday.