Not entirely sure what you mean by your question so I'll give the possible answers
1. Yes, you can jump in the game, by pressing space bar. If you press escape and open your menu you can change hotkeys and change it to a different key on your keyboard to jump.
2. If you meant that you are playing and can't jump--you may have moved it to a hotkey which you don't know; or if you are on a mount you can't jump while standing, only while moving.
Sentences are defined as having a verbal form. Since jump is a verb it also can technically be a sentence. It is then used in the imperative (commanding) form, issueing a command or urging for someone to jump.
In this way it is followed with an exclamation mark rather than a period.
"Can you jump over the hurdles in the race?"
How long did you want the sentence to be? The frog was a competitor in the Animal Olympics long jump event. Frogs can jump long distances.
"Jump on the bandwagon" IS a sentence.
She jumped the gun. She started at 3, when the other started at GO!
Walk to the edge and jump in the waterWalk and jump are both verbs.
He did a triple jump kick flip!
"You may not jump on your bed."
It is illegal to jump the turnstile.
The fall of the bungee jump was precipitous. This is an example sentence of precipitous.
The nouns in the sentence are Joe, a proper noun, jump and class, both common nouns.
Example sentence - We watched the children jump into the pool.
I can jump over a small fence.My horse jumps really well.