登录站点

用户名

密码

注册


 
使用帮助          普特英语口语训练软件!

标题新东方37-2 分类12 查看3482 上传62

正文

Also, they may roll over unexpectedly, churning the waters around them.

Icebergs are parts of glaciers that break off, drift into the water, float about awhile, and finally melt. Icebergs afloat today are made of snowflakes that have fallen over long ages of time. They embody snows that drifted down hundreds, or many thousands, or in some cases maybe a million years ago. The snows fell in polar regions and on cold mountains, where they melted only a little or not at all, and so collected to great depths over the years and centuries.

As each year’s snow accumulation lay on the surface, evaporation and melting caused the snowflakes slowly to lose their feathery points and become tiny grains of ice. When new snow fell on top of the old, it too turned to icy grains. So blankets of snow and ice grains mounted layer upon layer and were of such great thickness that the weight of the upper layers compressed the lower ones. With time and pressure from above, the many small ice grains joined and changed to larger crystals, and eventually the deeper crystals merged into a solid mass of ice.

本期优秀作品

暂无优秀作品

最新上传

[lovekarrier]   新东方37-2
2015-07-13
[hjplearn]   新东方37-2
2014-11-26
[lhxcxx]   新东方37-2
2014-10-26
[cai帅]   新东方37-2
2014-02-18
[cai帅]   新东方37-2
2014-02-18
[ivy-zz]   新东方37-2
2014-02-16
[myds2]   新东方37-2
2013-10-14
[lilyzuoting]   新东方37-2
2013-07-10
[sxdkdxz]   新东方37-2
2013-06-17