Dimension the distance between concentric curved surfaces.
Select the Tangent Feature button
Select Curved Features
Right-Click and select concentric
That will allow for dimensions such as shown above.
Blanking / Showing Lines
Select The Table
Right-Click to pull up this menu
Select Line Display
That will bring up this menu:
To modify the view state of a single line segment, select Blank or Unblank. Alternatively you can Unblank All