a/the fly in the ointment美中不足之处。
It was a real gorgeous day to go to the beach,sunny, breezy and the temperature was about 78. But the fly in the ointment was that Mike and I both cut our feet on some sharp coral.那天真是去海滨的好时光：阳光明媚、微风拂人，而气温大约七十八度。 但是叫人败兴的是Mike和我的脚都被尖锐的珊瑚刮破了。
Your new job sounds too good to be true--interesting work, high pay, short hours. Isn't there any fly in the ointment? 你的新工作听起来实在太好了--工作有趣味，待遇高，时间短。有什么美中不足的地方吗？
Another hotel seems to be a fly in the ointment, blocking part of the beautiful ocean view. 美中不足的是有另外一家旅馆挡住了部分美丽的海景。
I find the house wonderful, but there is a fly in the ointment：it is too far from the town. 我觉得那所房子非常好，但是有点美中不足，就是离市区太远了。