The author's intention is to keep everyone guessing until the bitter end.

这位作者的意图是在最终结尾前让所有人都猜不透。

《柯林斯英汉双解大词典》

Until the bitter end, the emptiness inside her was hers alone.

直到这痛苦的终点，她的虚空只是她自己的。

youdao

Poles remained loyal to him until the bitter end, with Polish units holding their ground at his last battles (battle of Leipzig and battle of Waterloo).

波兰士兵始终保持着无限的忠诚，哪怕直到最后苦涩的结局。

youdao

They accepted specious logic about what limited government means, right up until the bitter end.

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With the easterlies persisting through much of next week too, the cold could well hang on until the bitter end of March.

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And Musharraf, though weaker now, sees himself as a commando a man who prides himself on fighting his corner until the bitter end.

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