Their documentation can be used in the future as a study tool and for language protection efforts,if needed.

VOA: special.2009.12.02

it's too easy but it's also too delicious to take this little biographical fact of Milton's college nickname and use it in some way as a tool for reading A Mask.

这简单却有趣,把弥尔顿大学时的昵称记事,利用并作为一种工具去阅读《面具》

耶鲁公开课 - 弥尔顿课程节选

So, think about the birches as a tool, another tool, but this time a tool for play, a tool for playing alone.

把桦树看成一种工具，另一种工具，但是这次是玩的工具，只是玩的工具。

耶鲁公开课 - 现代诗歌课程节选

The Pakistani government has repeatedly said such attacks kill mostly civilians and only serve as a recruitment tool for Islamic militants.

VOA: standard.2009.06.03