What are the keywords in the following sentence? small rowing boat sitting on a beach at low tide
beach, sit, tide

What are the keywords in the following sentence? traffic is building approaching bridge
approach, bridge, traffic

What are the keywords in the following sentence? rapidly building cloud screening the sun with an aircraft in the sky
aircraft, sky, sun

What are the keywords in the following sentence? fishing boat passes along suspension bridge during sunset on a foggy evening
boat, bridge, pass, sunset