a stack of firewood的用法和样例：
- Grandpa stood watching him a bit, and then said, "There's a stack of firewood against the fence behind the barn.
- Lin stood in the yard facing the front wall while flipping over a dozen mildewed books he had left to be sunned on a stack of firewood.
- There is a stack of dishes to be washed in the kitchen.
- There are a stack of replies to our advertisement.
- A stack of hay or other feed stored in a barn.