Are the lines in the diagram perpendicular, parallel, skew, or none of these?

l and m:

l and n:

m and n:

are the lines in the diagram perpendicular, parallel, skew, or none of these?

l and m:

l and n:

Are the lines in the diagram perpendicular, parallel, skew, or none of these?

l and m: neither
l and m intersect, but are not perpendicular. 

l and n: skew
l and n are not parallel, but they do not intersect because they are not on the same plane. 

m and n: perpendicular.
m and n intersect at a right angle

Where's the rest of the