I think using unless with else is like speaking with double negatives.

我认为使用unless加else条件句就好像在讲双重否定。

youdao

Merely helping a gift-giver gain access to other officials, unless done with clear intent to pressure those officials, is not corruption, the justices found.

法官们发现，除非有明确意图向那些官员施加压力，否则仅帮助送礼者与其他官员接触机会就不是腐败。

youdao

I sleep with the window open unless it's really cold.

天气若不很冷，我总开着窗户睡觉。

《牛津词典》

Senators can threaten a bill with unlimited debate unless sixty senators vote to prevent it.

VOA: special.2010.01.23

I mean post 911 we had circumstances that a lot of people, unless you're actually dealing with it, you wouldn't really be able to understand what people are going through.

11之后我们的情况是,除非你真的在应对这件事,许多人都不是真的，能够了解,我们经历了什么。

普林斯顿公开课 - 人性课程节选

So, that means he's got to make his line unless he comes up with some clever trick, the same size as the other guy.

所以,这意味着除非他想出别的好点子,否则他就必须使他那一排的规模,和对方的一样

耶鲁公开课 - 古希腊历史简介课程节选

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