BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective and exploded view of a first embodiment of an adjustable cup-holder of the present invention; FIG. 2 is a partial sectional view of the first embodiment of the adjustable cup-holder of the present invention; FIG. 3 is a partial sectional view of a bottom portion structure of the first embodiment of the adjustable cup-holder of the present i