Data Tree urgent help!!!!!!

[anadionisio257 at gmail.com]

Hello! 
I have this lists with information and I need to make a "tree" by associating the information inside the lists. For example:

l1 = [apple, pear]
l2 = [dog, cat]
l3 = [fork, spoon]

And I need to make something like this:

l4 = [apple, dog, fork]
l5 = [apple, dog, spoon]
l6= [apple, cat, fork]
l7 = [apple, cat, spoon]
l8 = [pear, dog, fork]
etc...

How can I do this? I could use "for" cycles and "if...else" but with larger lists it gets complicated   

Is there some simple solution that I can use?

I hope you could help me