I lay it down as a general rule.

我认为这是一条准则。

He will not lay it down until it is finished.

不做完这件事他是不会放下它的。

I must soon lay it down, and commence living on its hint.

我要很快将它放下，开始按它的提示生活。

I must soon lay it down, and commence living on its hint.

我必须很快放下书，而且按照书上的建议开始生活。

Lay it down and make sure it's in the right position, right?

确保把它们放在合适的位置，我说的对吧？