'partial' keyword in C# is very good for project , what's the same thing in D?

[Andrea Fontana via Digitalmars-d]

On Wednesday, 29 October 2014 at 12:55:01 UTC, FrankLike wrote:
> The same thing in D should be done,now.Otherwise，no big 
> projects can be done like C#. Add another keyword,and update 
> the compiler.
>
> FrankLike

I wonder how linux was written in c.
I think it's a rather big project to do without partial keyword.