What are the keywords in the following sentence? soldier guarding the road to the border into country
guard, road, soldier

What are the keywords in the following sentence? freight train rounds a bend in hills above us state
bend, hill, round, state, train

What are the keywords in the following sentence? time lapse of clouds moving over the main tower and surrounding structures .
cloud, lapse, move, surround

What are the keywords in the following sentence? the original gate to the city built centuries before builder was born .
bear, build, builder