参考答案：

　　81. Children./ For children. / It's for children.

　　82. Because they think being close to nature is good for children.

　　/Because they think the survival activities are good for children.

　　83. They usually watch TV and play computer games./To watch TV and play computer games./Watching TV and playing computer games./What they do is to watch TV and play computer games./What they do is watching TV and playing computer games.

　　84. They don't know what to do./They feel uncomfortable (terrible)./Not comfortable.

　　/Uncomfortable./Terrible./ They don't feel comfortable.

　　85. They can learn some survival skills. / They can learn to stay calm in different times, keep safe and work in team. （只给出其中一点赋1分，若时态写成完成时赋1分。）