At the age of 12, the human body is at its most vigorous. It has yet to reach its full size and 【T1】 1, and its owner gets his or her full 【T2】 2. But at this age the likelihood of death is least. Earlier, we were 【T3】 3 and young children, and consequently more vulnerable. Later, we shall 【T4】 4 a progressive loss of our vigor and 【T5】 5which, though imperceptible (难以察觉的) at first, will finally become so 【T6】 6that we can live no longer, however well we look after ourselves, and however well society and our doctors look after us.
This decline in vigor with the 【T7】 7of time is called aging. 【T8】 8. Even if we escape wars, accidents and disease, we shall eventually die of old age. 【T9】 9. Some of us will die sooner: a few will live longer. 【T10】 10, however lucky and robust (强健的) we are. 【T1】