Can you run an SFP module and cable in an SFP+ port?

So if I have some open SFP+ ports on my router or switch are they backwards compatible to use just regular SFP modules and cables to run just an SFP cable if I wanted to? I ask because obviously single mode SFP cable is cheaper than the 10g stuff for longer runs that I would like to make.

Hi,

I know on the CRS226 that the left SFP+ module (as you look at the front) is capable of using an SFP module. Not sure about any other models.