A real and pressing issue is that many plant species have not yet been cataloged, and so their place in the ecosystem is unknown.

一个现实而紧迫的问题是，许多植物物种还没有被编目，因此它们在生态系统中的位置是未知的。

youdao

It will insist on the fact that agriculture will not be confronted with unknown situations and that solutions do exist; that we must work with climate change, not against it.

文件将坚持这一事实：农业不会面临未知的情景，确实存在解决办法，而我们必须面对气候变化进行工作，而不是极力扭转它。

youdao

This protects you from unknown notifications which could be implemented in the future, and that your program might not be able to handle.

这就避免了将来遇到可能可以实现，但是程序却无法处理的的未知的通知。

youdao

"The situation is somehow much more unknown to the Western world and was not particularly described in the media and it was particularly touching."

VOA: standard.2010.06.29

Many combinations are possible and the very fact that the outcome is unknown, and is not being dictated by the state, is a sign of progress.

ECONOMIST: Business in Russia

"It'll be a British style game and it's not the unknown quantity we could have had, " he added.

BBC: [an error occurred while processing this directive]

But he was careful not to overstate the case: "The full promise of stem cell research remains unknown, and it should not be overstated" he said.

BBC: Another Bush policy overturned