a knockout blow的用法和样例：
- Clinton's strategy had been premised on delivering a knockout blow early.If she could win Iowa, she believed, the race would be over.
- The fight was won by a knockout.
- He has a knockout of a girlfriend.
- Seeing the opponent was off guarded, the boxer landed a knockout punch.
- You really look a knockout in your new dress.
- To defeat(a boxing opponent) by a knockout.