I made a bit of a boob throwing that file away.

我犯了个愚蠢的错误，把那份文件扔掉了。

I saw the policemen file away a moment ago.

刚才我看见警察排成一列纵队出发了。

You have to file away for hours to get this metal smooth.

你要想你这块金属光滑，必须用锉刀不停地锉上几小时。

You have to file away for hours to get this metal smooth.

你得锉上几个小时才能使这金属变得光滑。

You have to file away for hours to get this metal smooth.

你得锉好几个小时才能锉平这块金属。