a knock-down punch的用法和样例：
- The champion knocked down his opponent in the second round with a Sunday punch.
- In the second that the boxer was off guard, his opponent landed a knock out punch.
- How much does he knock down a week?
- He manages to knock down a guard and grab a knife.
- It may be advantageous for a firm to ship abroad the components of its final product in a knocked down condition.