6. There's the Rub: 這就是問題所在

How Shakespeare used it:

In Hamlet's famous "To be or not to be" soliloquy, "ay, there's the rub" is the tormented prince's acknowledgement that death may not end his difficulties because the dead may perhaps still be troubled by dreams. (Hamlet, Act 3, Scene 1)

莎士比亞原文：在《哈姆雷特》那句著名的“生存或者死亡”獨白中，“唉，這就是問題所在”表示飽受折磨的王子認識到，死亡并不能結束他的痛苦，因為死人可能仍然會被夢境困擾。（《哈姆雷特》，第3幕第1場）

現代例句：

"There's the rub. What does a progressive institution like Smith [College] do when Barbara decides to become Bert? It's a problem." — Roger Kimball, The New Criterion, May 2005