(I) The first men to climb to the summit of Mount Everest were Sir Edmund Hillary, and his companion, Sherpa Tensing. (II) They were also the first climbers to take oxygen equipment with them, (III) The equipment made it possible for them to rest and sleep at very high altitudes. (IV) Normally people suffer from lack of oxygen at very high altitudes, for the partial pressure of oxygen is then too low. (V) They had a very well organised base camp and a team of experts to back them up, without whom, They both said, the climb couldn't have been achieved.