Thank you very much for your helps. I understand. But I could not do it.
I added a circle curve. and I attach a polygone to it. its okey.
And it turning slow - fast - slow.
And I click the curve and I open the graph editor. I cick Tangents on tabs and select Linear.
But there is not any difference.
Sorry for I didnot get it. Maybe its so simple but I am beginner on maya
Could you tell me step by step please. I am not clever a student :$