What are the keywords in the following sentence? rocks on the bottom of a sea
bottom, rock, sea

What are the keywords in the following sentence? warm water causes a mist to rise
mist, rise, water

What are the keywords in the following sentence? time lapse of clouds over mountain range during the summer
cloud, range, summer

What are the keywords in the following sentence? a tent sits below the aurora borealis .
borealis, sit, tent