a fly in the ointment美中不足
该词组指美中不足。如：
We had a great holiday. The only fly in the ointment was that Robert had a bad cold for the first few days.
我们的假期很棒。唯一美中不足的是罗伯特在头几天患了重感冒。
这一表达出自“钦定版”《圣经》中《传道书》（Ecclesiastes ）第10章第1节：
“Dead flies cause the ointment of the apothecary to send forth a stinking savour.”
“死苍蝇使作香的膏油发出臭气。”
