a woollen mill的用法和样例：
- He wore a woollen vest beneath his shirt.
- Cotton cloth is made in a cotton mill.
- The mill where we often labour is a paper mill.
- On the outskirts they passed a steel mill.
- One day they wrote to her that her little Cosette was entirely naked in that cold weather, that she needed a woollen skirt, and that her mother must send at least ten francs for this.