They feed on tiny things in sea water and help to keep the water clean in the process.

它们以海水中的微小物体为食，并在这个过程中帮助保持海水的清洁。

youdao

Let's do our best to keep the water clean to save ourselves.

让我们尽力保持水的清洁来拯救自己。

youdao

Now, we have to shave our heads to keep them clean without the use of water.

现在，我们必须剃光头，从而在不使用水的情况下保持清洁。

youdao

At certain moments the air streamed against the ship as if sucked through a tunnel with a concentrated solid force of impact that seemed to lift her clean out of the water and keep her up for an instant with only a quiver running through her from end to end.

FORBES: Has Sandy Capsized Your Life? Here's One Thing To Be Thankful For

Government are teachers in the classroom. (Applause.) Government are our firefighters and our police officers, and the folks who keep our water clean and our air clean to breathe, and our agricultural workers.

WHITEHOUSE: President Obama��s Town Hall in Cannon Falls, Minnesota