综合性学习。

    学习了本文后，班级组织了一次以“我想我是海”为主题的教育活动，请你参与并完成以下任务。

    Two men walked through the countryside toward another village. As they come to the edge of a river, they saw an old woman sitting there upset because the bridge was____by the storm, and she was too weak to walk across the stream. The first man said____, “We are tall enough, and we can carry you across” The second man thought it troublesome, but he agreed reluctantly（不情愿地）. So the two men ____ the bridge, lifted her between them and carried her across the river. When they got to the other side, they set her down and she went on her way gratefully. After they had walked another mile or so, the second man began to complain “My back began to hurt for lifting her.” The first man ____ smiled and nodded without a word.

血红蛋白是一种含____的蛋白质。它有着这样的特性：在氧含量高的地方容易与氧____，在氧含量____地方容易与氧容易分离。