a crusty cob的用法和样例：
- He's a crusty old gentleman who feeds stray dogs and cats.
- It appeared as a rash, which later became a lesion with a crusty outer edge.
- Piping hot and creamy clam chowder served in a crusty golden-brown home made bread.
- A wonderful doctor named Robert Yanover took me to a crusty, briliant old craftsman named George Dorsch.
a crusty cob的相关资料：