1. Almost any day a young porpoise may be seen trying to turn a 300-pound sea turtle over by sticking his snout under the edge of his shell and pushing up for dear life.
    几乎每天都可以看到一只小海豚把鼻子顶入一只300磅重的海龟的硬壳下面，拼命地把它翻过来。

2. "For a woman who already has a poor iron status, any additional iron loss from exercise may be enough to tip her over the edge into a more serious deficiency," notes the expert.
    他提醒说，"对于那些已经缺铁的女性，任何因锻炼而产生的更多铁离子流失都足以导致体内缺铁状况的恶化。"

3. Once on the edge of the educational system, such schools, or jukus, are now so common in Japan that, especially for those people at the top level of society, they have begun to function as a kind of shadow educational system, replacing regular school
    这些专门对付考试的课外学校（日语中称为juku），曾是教育体制的次要成分，如今却在日本非常普及，尤其对上层社会的人群而言，它们已经开始成了一种影子教育体制，在家长和学生、乃至两三岁的孩童心目中，它们的重要性已经取代了正规学校。

4. It is dangerous to walk near the edge of a cliff.
    在悬崖边行走是危险的。

5. I could hear birds whistling at the edge of the woods, and the Prussians drilling in the meadow behind the sawmill.
    我可以听到鸟儿在树林边的叫声和普鲁士士兵在锯木厂后边草地上操练的声音.

6. I could hear birds whistling at the edge of the woods, and the Prussians drilling in the meadow behind the sawmill.
    我可以听到鸟儿在树林边的叫声和普鲁士士兵在锯木厂后边草地上操练的声音.

7. I could hear the bird whistling at the edge of the woods.
    我可以听到小鸟在树林边婉转地歌唱。