Those who have a strong love for climbing high and difficult mountains are often looked upon with astonishment. Why are men and women 1_______ to suffer cold and hardship, and to 2_______ on high mountains? This astonishment is caused, probably, by the difference between mountaineering and other forms of activity 3_______ men give their leisure.
Mountaineering is a sport and not a game. There are no man-made rules, as there are for such games as golf and football. There are rules of a different kind which it would be dangerous to 4_______. but it is this freedom from man-made rules 5_______ makes mountaineering interesting to many people. Those who climb mountains are free to use their own methods.
If we compare mountaineering with other more 6_______ sports, we might think that one big difference is that mountaineering is not a "team game". We should not be 7_______ in this. There are, 8_______ , no "matches” between "teams” of climbers, but when climbers are on a 9_______ linked by a rope on which their lives may 10_______ , there is obviously teamwork.
The mountain climber knows that he may have to fight forces that are stronger and more powerful than man. He has to fight the forces of 11_______.This sport requires high physical and mental 12_______ .
A mountain climber continues to improve in skill year after year. A skier is probably 13_______ his best by the age of thirty, and most international tennis champions are in their early twenties. But it is not 14_______ for men of fifty or sixty to climb the highest mountains. They may take more time than younger men but they probably climb with more skills and less 15_______ of effort.They certainly experience equal enjoyment.
5
A、what
B、it
C、that
D、which
【正确答案】：C
【题目解析】：译文：但是正是因为没有人为制定的规则，才使得许多人对登山感兴趣。分析句子结构知此处是“It is+强调部分+that从句"构成的强调句，C符合题意，其他三项不能引导强调句。答案为C。
