What are the keywords in the following sentence? woman lying in a field of wheat
field, lie, wheat

What are the keywords in the following sentence? friendly nurse talking with disabled patient at the hospital
hospital, nurse, patient, talk

What are the keywords in the following sentence? A traffic light indicating that cars going straight or to the right may proceed.
car, light, proceed

What are the keywords in the following sentence? an aircraft flies past the tower on its final flight over tourist attraction
aircraft, fly, tower