a stroke of lightning的用法和样例：
- But it descends with sudden force Like a stroke of lightning.
- A stroke of lightning shattered their mast, which in its fall killed the pilot.
- The lazy boy has not done a stroke of work all day.
- It was a stroke of luck that I found you here.
- Your idea was a stroke of genius!
- Curt never did a sortke of work. Catch him!