返回值 1-5,10-11%29*this 6-9%29一个迭代器,它指的是第一个插入字符的副本或pos如果没有插入字符%28count==0或first==last或ilist.size()==0%29
"code":"23","name":"冶金"},{"code":"24","name":"有色金属"},{"code":"25","name":"建材"},{"code":"26","name":"医药