a picket fence的用法和样例：
- "It was lovely. It had a high mansard roof with a picket fence on top and a tower made of fancy shingles at each end.
- They marched to the factory and formed a picket.
- He worked his way to the white picket fence bordering their lot.
- A stake or pointed stick;a picket.
- A stake or pointed stick; a picket.