哪位大佬帮忙看看这段代码哪里错了呢

public interface Ibook
{
void showbook();
string GetTitle();
int GetPages();
void SetPages(int pages);
}
public class NewBook:Ibook
{
public string title;
public int Pages;
public string author;
public NewBook(string title,string author ,int pages)
{
this.title = title;
this.author = author;
this.Pages = pages;
}
public string GetTitle()
{
return title;
}
public int GetPages()
{
return Pages;
}
public void SetPages(int pages)
{
this.Pages = pages;
}
public void Showbook()
{
Console.WriteLine("title :{0}", title);
Console.WriteLine("author:{0}", author);
Console.WriteLine("pages:{0}", Pages);
}
}
public class Program
{
static void Main(string[] args)
{
NewBook nb = new NewBook("China dream ","robert",500);
nb.Showbook();
Console.Read()；
}
}
}
哪位大佬帮忙看下这段代码 哪里错了 呢 错误显示 NewBook不实现接口成员