题目

Most young people enjoy some form of physical activity. It may be walking, cycling, or swimming, or in winter, skating or skiing. It may be game of some kind football, hockey, golf, or tennis. It may be mountaineering. Those who have a passion for climbing high and difficult mountains are often looked upon with astonishment. Why are men and women willing to suffer cold and hardship, and to take risks on high mountains? This astonishment is caused probably by the difference between mountaineering and other forms of activity to which men give their relaxation. Mountaineering is a sport an分子与原子间最本质的是（    ）A.大小不同                        B.能否直接构成物质   C.能否保持物质化学性质             D.化学变化中能否再分