the penny drops
US /ðə ˈpɛni drɑps/
UK /ðə ˈpɛni drɑps/
1.
恍然大悟, 终于明白
used to say that someone has finally understood something, especially after a period of not understanding
:
•
It took him a while, but then the penny dropped and he realized his mistake.
他花了一段时间，但后来他终于明白了，并意识到自己的错误。
•
I kept explaining, but it wasn't until I drew a diagram that the penny dropped.
我一直在解释，但直到我画了图表，他才恍然大悟。