What are the keywords in the following sentence? The pizza box has been left with two leftover pieces.
box, leave, piece

What are the keywords in the following sentence? A teenage boy enters the room and approaches him from behind.
approach, enter, room

What are the keywords in the following sentence? players gathered at the charity football match .
gather, match, player

What are the keywords in the following sentence? an unique feature of markets is that customers have to bag their own groceries .
bag, customer, grocery