Controling the x or y limit

Hello - R-experts,

This may sound simple to many --- 

We can specify the x limit by saying xlim = c(0, 20) for example.
Then the graph will show the range of x -axis between 0 - 20.
But the coordinate gap will be automatic like 0 then 5 then 15 and 20. 
Is there any way by which we can set it in a gap of 2 or any number.


Thank you for any help.

With Regards

Subhabrata