Summer passed, autumn passed, winter came again, camel team came again, but childhood never came back, expressing the author's mood.

Summer passed, autumn passed, and the camel team came again, indicating that time passed, but childhood never came back. Expressed the author's memory of childhood, yearning for childhood, and time passed again. However, the vivid memories and good feelings of childhood can not pass, expressing the author's regret that it is difficult to meet again with the passage of time.