Possible answers to P. 550 #2 (a-g) are:
 

1. one pair:  BD and GH;  another pair: EH and CD  (note: these should have the line symbol over them, but that is difficult to get into a web page.)
2. they are parallel.
3. No, they are skew.
4. The intersection is the empty set (they don't intersect).
5. The intersection is the point H.
6. one pair:  BCG and DCG; another pair: EFH and ABF.
7. AE and CG.