Maybe they "stop" because there isn't enough money to take the next step, or they are afraid to leave the certain safety and security of their current job to change careers - the fear of the unknown.

也许，我们不得不停下来，因为没有足够的钱去迈出下一步，也或者我们害怕离开固有的安全保障，害怕因改变自己的事业而失去现有的稳定工作——对未知的一种恐惧。

youdao

The any element also enables certain scenarios where other unknown content models are valid, and their validation can be handled by the schema associated with that element's namespace content.

any元素也可用于这样的场合：其他未知内容模型是有效的，其验证可由模式和该元素的名称空间内容来处理。

youdao

For example, certain letters or words are more likely to occur together-if an unknown keystroke follows a "t", it is much more likely to be an "h" than an "x".

例如，一些字母或单词更容易同时出现——如果一次未知的键击跟随在“t”之后，那么它是“h”的可能性就比是“x”大很多。

youdao

In the world of IT, we often rely on the fact that the real world claimant of any information who must then be authenticated, before he may be permitted the use of his information, will also possess and may timely share certain secrets unknown to anyone else.

ECONOMIST: Fake ID cards

The exact mechanism is unknown, but certain bacteria are thought to facilitate important interactions between the gut and the brain.

WSJ: A Gut Check for Many Ailments

"The sell-off is a step into the unknown in that we cannot be certain that it would provide service equal to that provided by the RAF, " said Mr Jones.

BBC: Helicopter search and rescue for Caernarfon, St Athan