a pocket of air的用法和样例：
- We sat in a pocket of warmth by the fire.
- They sat in a pocket of warmth by the fire.
- I got a pocket, got a pocketful of sunshine.
- Most entrepreneurs have a pocketful of ideas, many of them viable.
- The trouble with the new pound coins is that you think you've only got a pocketful of small change but in fact it's worth several pounds.