The Twin Boxing style is the secret. Its power and speed are too much for you. You're not strong enough.
10 seconds sound clip from the The Woman Avenger (1980) movie soundboard.
You can hear this line at 01:06:34 in the DVD version of the movie.
Quote context
[...]
- But for me, it's been hard, my leg stopped me.
- I have been waiting for someone who could fight on my behalf. At last, I think I've found her.
- Your kung fu is no good. You could never hold hope to match Quang Wu Chi in a fight.
- But there must be some way to defeat it.
- And you must also learn my special kicking technique, which is know as Tin Shan Feet.
- Both together we can defeat him, believe me, it is possible for us to defeat him.
[...]