on a higher floor; on a lower floor; on a regular basis; on air; on all fours; on an individual basis; on an irregular basis; on and off; on approval; on average; on board; on camera; on earth; on faith; on fire; on guard; on hand; on it; on occasion; on one hand; on one's guard; on paper; on purpose; on request; on tap; on that; on the average; on the button; on the coattails; on the contrary; on the dot; on the face of it; on the fence; on the fly; on the go; on the hook; on the job; on the loose; on the nose; on the offensive; on the one hand; on the other hand; on the q.t.; on the qt; on the qui vive; on the road; on the side; on the sly; on the spot; on the spur of the moment; on the table; on the way; on the whole; on the wing; on time; on tour; on trial; on your guard; on-going; on-key; on-license; on-line; on-line database; on-off switch; on-site; on-street; on-the-job; on-the-scene; on-the-spot;