a rare chance的用法和样例：
- Humanity is facing a rare chance for development as well as tough challenges in the new century.
- It would be a rare chance, somewhat increased if there was a an Assaultman, FO, or Marksman.
- In China today, it is a rare chance indeed to see an authentic painting by Su Dongpo.
- The enactment of Civil Code affords a rare chance for the improvement of invalid marriage institution in China.
- Under this situation, higher professional education exposes its unfitness and it is also faced with a rare chance.