该词组指意外且令人震惊的事件。如：
- Her dismissal came as a bolt from the blue.
她被解雇简直就是晴天霹雳。 - The company decided to appoint a Japanese manager as president of the company. The decision came as a bolt from the blue.
公司决定任命一位日籍经理担任总裁。这个决定太出乎意料了。
其中 blue指晴天，晴天里的雷电自然令人震惊不已。
