10. The book Practicing: A Musician's Return to Music mainly tells that ______.
C
[解析] 根据文中最后一段的内容“Everyone who gives up a serious childhood dream-of becoming an artist, a doctor, an engineer, an athlete-lives the rest of their life with a sense of loss, with nagging what it is," he writes. "Is that time and effort, that talent and ambition, truly wasted?”可知,C项“没有梦想的生活是不完整的”符合题意。A项“挫折会使一个人很痛苦”,B项“旧梦复燃很有益处”,A、B两项在文中虽有体现,却不是《实践:音乐回归之旅》所要表达的主题,D项“音乐家经历挫折是在所难免的”,这个说法太绝对。