Hi, I'm making an animation but something looks wrong with this part. I don't know.
http://sta.sh/06y7lgpuzf5

Could it be the fact that none of your limbs are attached or that you're double framing randomly? Are you using onion skin at all or running through the frames as you animate to make sure you have fluid movements? Easing is also not relevant here at all :(

I don't know how to use double frames correctly, I use onion skin and I don't know what does mean easing (I also used Reverso/Google translate, and I got words related to lightweight ) . I don't like line tool but if I use brush tool, those arms may be deformed. I don't know how to use line tool actually.

I think I made something wrong this those frames. Triple and quadruple framing, a bad idea.

Since English isn't your first language, I tried to use as many visuals as I could with this.

http://sta.sh/010jeodr6yj6

Green: This is the easiest method to learn and looks good.
Yellow: Usually don't double frame when you start movements.
Bright Green: I prefer to double frame when easing out as it usually looks better with fast moving objects.
Red: This is what you did. Don't randomly double, triple, or quadruple frame.

Easing: Easing is essentially the way everything moves, and is more noticeable with object that are heavier. Another term that is similar is momentum. It's like when you get in a car and begin to accelerate, you don't accelerate in intervals of five or ten, but you slowly accelerate up to the maximum speed. You start out slow at first, but as the car builds up momentum it will speed up quickly. When you press on the brakes, you will begin to gradually slow down until you eventually stop. Everything you animate has easing. Every limb on a stick figure eases differently depending on how you moved them, etc.

Thanks for your help, now I understand better what is easing :D