Here is another one of my favorite left hand exercises. Practice it to develop more finger independence and to help stabilize your fixed fingers. The destabilizing element of the slur adds a challenge. Like in the first contrapuntal exercise, go slowly to insure the voices are being held their full duration. You can easily (or maybe with a lot of struggle) create a more challenging exercise by increasing the distance between the strings in use and by maintaining good form. Focus on the vertical movement of the fingers while the left hand remains stable. Use less hand tilting to get to the lower (or higher) strings.