a wicked grin的用法和样例：
- This small, thin humanoid has two long horns and bright yellow eyes. A wicked grin spreads across its narrow face a ball of flame materializes in its palm.
- The little boy had a wicked twinkle in his eyes.
- He plays a wicked game of bridge.
- She is in the grasp of a wicked man.
- A wicked prank; a critic's wicked wit.