It is true that times are changing for the old people in Britain．But not all the changes are bad ones．Modern medicine, for example, has made people healthier than they used to be．Old people, too, have more money now than their own parents and grandparents had．
But there still exist some more disadvantages(缺点)．The biggest disadvantage of modern life is loneliness．The young leave home when they grow up and many old people live by themselves．Fewer old people have brothers and sisters．An old person's one or two children may have moved to another part of the country．Even when they live nearby, the young people have their own children to look after．They do not have much time for the old．Loneliness often start when people stop working．When people retire(退休)，they often find it difficult to start a new life without their jobs．
The world has changed so fast since 1900 that it is difficult for old people to understand the problems of the young．And the world is changing even faster these days than it was fifty years ago．What will it be like when today's young people are old?
(1)
The old find it difficult to understand the young, because ________．
