What are the keywords in the following sentence? cirrus clouds against a blue sky in summer
cloud, sky, summer

What are the keywords in the following sentence? a helicopter flies away with its own hangar .
fly, hangar, helicopter

What are the keywords in the following sentence? The kids here are participating in a similar activity.
activity, kid, participate

What are the keywords in the following sentence? sport car based on automobile model
base, car, model