1.When you lose you're balance and drop to the floor.
A.trips B.slips C.falls D.all of the above
2.Hit an object,lose you're balance and fall.
A.trips B.slips C.falls D.none of the above
3.It refers to biological substance that pose a threat to the health of living organism,primarily that of human.
A.biological hazard's B.botanical hazards C.sociological hazards D.psychological hazards