What are the keywords in the following sentence? the trail follows a city down
city, follow, trail

What are the keywords in the following sentence? a shepherd and a herd of sheeps
herd, sheep, shepherd

What are the keywords in the following sentence? An airport field with a plane being boarded.
board, field, plane

What are the keywords in the following sentence? i like the railing for the stairs .
like, rail, stair