Geometry Help.?

Question

Can someone help me with some of these I'm a tad bit confused. Also, telling me why and how it is would be awesome.

1. Can two opposite rays (always,sometimes,or never) form a line

2. Two skew lines are (always,sometimes,or never) coplanar

3. Two Planes that do not intersect are (always,sometimes,or never) parallel

4. Two Lines in intersecting planes are (always,sometimes,or never) skew.

Answer 1

1. always
2. never
3. always
4. sometimes