Okay,
Under Edit, go to preferences/guides and grid, set up your grid to the spacing you desire, Under View, set Snap to grid, create your object then use my previous instructions to "repeat" your original object, Ctrl D to achieve the desired result.
Solution 2:
Create your object, knowing in advance the overall distance that you wish them to span, copy the object and set it at the furthest most point, On your tool bar use the Blend tool, click on the first copy and then again on the second copy. By default the Blend tool is set to "Smooth Color", not the effect you want, double click the blend tool on the tool bar to bring up its options, in the drop down menu choose "Specified distance" or Specified steps"