Question

parallel
lines that never
are used to indicate the lines are parallel
symbolic notation:
parallel
planes
that never
symbolic notation:
skew
lines that never
examples: &
&
&

Explanation:

Parallel lines are coplanar lines that never intersect. Arrows are used to indicate lines are parallel and the symbolic notation is $\parallel$. Parallel planes are planes that never intersect and the symbolic notation is $\parallel$ for planes too. Skew lines are non - coplanar lines that never intersect. In a cube, for example, edge $TW$ and edge $PQ$ are skew lines, also edge $TV$ and edge $QR$ are skew lines.

Answer:

Parallel lines: Coplanar lines that never intersect; Arrows; $\parallel$
Parallel planes: Planes that never intersect; $\parallel$
Skew lines: Non - coplanar lines that never intersect; Examples: $TW$ & $PQ$, $TV$ & $QR$