填空题 How often one hears children wishing they were grown up, and old people wishing they were young again. Each age has its {{U}}(11) {{/U}} and its pains, and the happiest person is the one who enjoys what each age gives him without wasting his time in {{U}}(12) {{/U}}. Childhood is a time when there are few {{U}}(13) {{/U}} to make life difficult. If a child has good parents, he is fed, looked after and loved, whatever he may do. It is {{U}}(14) {{/U}} that he will ever again in his life be given so much without having to do anything {{U}}(15) {{/U}}. In addition, life is always presenting new things to the child—things that have lost their interest for older people because they are too well known. But a child has his pains: he is not so free to do what he wishes to do; he is continually being told not to do things, or being punished for what he has done wrong.