Most young people enjoy physical activities, walking, cycling, football, or mountaineering. These who have a passion【C1】______climbing high and difficult mountains are often【C2】______with astonishment. Why are men and women【C3】______to suffer cold and hardship, and to【C4】______on high mountains? This astonishment is caused, probably, by the difference between mountaineering and other forms of activities【C5】______which men give their leisure. There are no man-made rules, as there are for【C6】______games as golf and football. There are, of course, rules of different kinds which it would be dangerous to【C7】______, but it is this freedom from man-made rules【C8】______makes mountaineering attractive to many people. Those who climb mountains are free to use their own【C9】______. If we【C10】______mountaineering with other more familiar sports, we might think that one big difference is【C11】______mountaineering is not a 'team work'. However, it is only our misunderstanding. There are, in fact, no 'matches'【C12】______'teams' of climbers, but when climbers are on a rock face linked by a rope on which their lives may【C13】______, obviously, there is teamwork. A mountain climber knows that he may have to fight with natural【C14】______that are stronger and more powerful than man. His sport requires high mental and【C15】______qualities. A mountain climber【C16】______to improve on skill year after year. A skier is probably past his best by the age of thirty, and most international tennis champions【C17】______in their early twenties. But it is not【C18】______for men of fifty or sixty to climb the highest mountains in the Alps. They may take more【C19】______than younger men, but they probably climb with more skill and less【C20】______of effort, and they certainly experience equal enjoyment. 【C1】