[填空题]
The Process of Ageing
At the age of twelve years, the human body is at its most vigorous. It has yet to reach its full size and strength, and its owner his or her full intelligence; but at this age the likelihood of death is the least. Earlier, we were infants and young children, and consequently more vulnerable; later, we shall undergo a progressive loss of our vigor resistance which, though imperceptible (察觉不出的) at first, will finally become so steep that we can live no longer, however well we look after ourselves, and however well society, and our doctors, look after us.
(46) . If we escape wars, accidents and diseases, we shall eventually "die of old age",
(47) .Some of us will die sooner, a few will live longer. But there is a virtual limit on how long we can hope to remain alive, however lucky and robust we are.
Normal people tend to forget this process until they are reminded of it. We are so familiar with the fa