This's the third one, and the last one also is the answer, the key to the question of the door.

这的第三个和最后一个也是答复，门的问题的钥匙。

youdao

Water is a key to the question of whether life, even in the form of microbes, ever existed on Mars. On Earth, all known forms of life require water.

水是一个是否有生命存在的关键问题，即使是以微生物的形式，火星上和地球上都曾经存在，所有已知的生命都需要水。

youdao

The key to the question is to judgment whether there is the legal relation of bills of lading stipulated of article 78 between the carriers and FOB seller .

此问题的关键是认定FOB卖方与承运人之间是否存在第78条所规定的提单法律关系。

youdao

Analysts say a key question is whether Russia will continue to insist missile defense be linked to the conclusion of an arms-control agreement.

VOA: standard.2009.07.15

Should we conclude,therefore, that the key to the important question--namely, What matters? the answer to that question, should we conclude,is,same personality?

我们是否就该得出结论，重要问题的关键，也就是什么是最重要的，这问题的答案就是相同的人格吗？

耶鲁公开课 - 死亡课程节选

What I'm considering right now is the question whether sameness of soul is the key to being the same person.

我现在考虑的问题是,同样的灵魂,是否就是成为同一个人的关键。

耶鲁公开课 - 死亡课程节选

The Higgs is the key to unlocking the question: Why does matter have mass?

CNN: Higgs and the holy grail of physics

The parliament holds the key to the second question: why Peter Mandelson did not become High Rep, though there is a good argument he would have been better than Lady Ashton, for all his abrasive style and weakness for intrigue.

ECONOMIST: European politics

Some key figures tackling the global recession found this paper a useful addition to the debate at the heart of which is this key question: is it best to let debt increase in the hope of stimulating economic growth to get out of the slump, or is it better to cut spending and raise taxes aggressively to get public debt under control?

BBC: News