Thanks, onlooker. I keep my body weight ,the region below my shoulder blades,hip and top of thigs vertically toward the floor , right heel off the floor, body on the center as Luca mentioned when I practiced on myself ; when dance with other one, the man put his almost total body wight on his left foot, I had to follow so. With same body line , over 80% of body weight was supported by my right BT, my left leg became straighter, I tried my best to extended my head upward and more backward to increase the volume. is it OK ?