1. Parallel
2. Perpendicular
3. Skew
4. Parallel
5. Perpendicular
6. ↔QW, ↔SW, ↔TZ
7. ↔YZ, ↔ST
8. ↔RQ, ↔QW, ↔ST, ↔TZ
9. Plane TQW, plane SRX, plane ZWX
10. Plane WXY
11. Corresponding
12. Alternate exterior
13. Alternate interior
14. Consecutive interior
15. Alternate exterior
16. Alternate interior
17. ↔OL ║↔VN
18. ↔VN ⊥ ↔RT
19. No; the markings do not indicate that the lines are parallel