What are the keywords in the following sentence? plant and carefully add soil to completely cover roots .
add, plant, root, soil

What are the keywords in the following sentence? close up portrait of cheerful students with teacher at the classroom
classroom, close, portrait, teacher

What are the keywords in the following sentence? half of a pizza sitting on a tray
half, pizza, tray

What are the keywords in the following sentence? a herd of fighting bulls grazing near an artificial lake
graze, herd, lake