In volleyball, the following actions are legal:
- Spike the ball: This is a primary offensive move in volleyball and is perfectly legal.
The other actions mentioned are generally not legal:
-
Touch the net during play: This results in a fault unless the player is completely out of the way and does not interfere with play.
-
Hit the ball twice in a row: This is not legal unless the player is attempting a block or the ball is contacted in a specific way as in a "double hit" during a single play.
-
Cross underneath the net during play: This is legal only if it does not interfere with the opposing team’s play, but generally, players may cross under the net if they do not violate any other rules.
So, the legal action from your list is spike the ball.