Hi, thanks.
I thought my weight is OK, that's because when I forewalk I used my supported leg to push my weight fwd, and just let my free leg swing ...
So my situations maybe more like Blair said.

On the same time, would you tell me where I can learn "Shape and line" from books, vedios, or internet?

Those "shape and line" I meant, just like Contra check, Lunge, The same foot lunge, Hinge, and so on in Waltz. When dancer are dancing those steps, they often held position and started using body action.... it's beatiful. I don't have any ideal about how to do that.

By the way "Progress side link in Tango(QQ)", from Tango Walk change into PP postion, I can see a very obvious body and hip action. But I still can not understand how to do it, my teacher just tell my use my knee close together and tuck in, those all, but I do as him said, it didn't work!
So.....

thanks in advance

john

Your instructor may be refering to body actions like contra body motion (CBM), sway, swing action and body flight. There is a brief description of these terms in the glossary on this site. These body actions take time to develop.

https://www.ballroomdancers.com/Learning_Center/Glossary/Default.htm