我认为使用unless加else条件句就好像在讲双重否定。

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

youdao

要模拟if - else场景中的else部分，请否定原始条件即可。

To simulate the else portion of an if-else scenario, negate the original condition.

youdao

通过证明延迟是由于保险人在签订保险合同之前已知道的情况造成的，或证明保险人已放弃该默示条件，该默示条件可以被否定。

The implied condition any be negative by showing that the delay was caused by circumstances known to the insurer before the contract was concluded, or by showing that he waived the condition.

youdao