His shoes dragged him down, and he could barely keep his head above water.

他的鞋把他往水里拽，他几乎不能让他的头伸到水面上了。

A man who loses his job tries to keep his head above water until he finds a new job. " Water over the dam" is another expression about a past event.

一个失业者在找到新工作之前往往也尽力保持头浮出水面。 “水漫过了水坝”是个有关于过去某事件的表达。

The cotton dress tied itself round his legs, trying to pull him under, and Toad had to fight to keep his head above water.

河水带着他向前流，一会儿把他推到这边，一会儿又推到那边。棉布外套裹住了他的腿，将他向下拽，他不得不挣扎着让头浮在水面上。

Dazed and bruised, but miraculously still alive, Harrison held on to an overturned washbasin to keep his head above water in the four foot square bathroom.

遍体鳞伤，但奇迹般地还活着，他抓住一个翻倒的洗脸盆， 让自己的头露出水面。