a free-will offering的用法和样例：
- A free will and a will subject to moral laws are one and the same.
- Kant understands rationality as the distinguishing feature of human beings, which enables them to have a free will.
- She seized on the offer of a free trip.
- I missed out on his offer on a free holiday in Spain.
- Write now to this address and we will send you a free sample by return.
- Free will makes us able to choose our way of life.