don't worry; there's no need to worry
police officer; policeman; policewoman
to rise; to go up; to enter (esp. from outdoors); to come in; to enter (a school); to advance to the next grade; to get out (of water)
stairs; stairway; staircase
to be in time (for); to serve (suit, meet) the purpose; to be good enough; to be enough
electrocardiograph; ECG; EKG
voice; singing (of a bird); chirping (of an insect); voice; opinion (as expressed in words); sound; sense (of something's arrival)