Cannot alias expression

[John Colvin]

I suspect I'm being very dumb here, but I can't get my head 
around this:

     template B(alias A)
     {
	alias B = A;
     }
     template C(A ...)
     {
	alias C = A[0];
     }
     static assert(B!1 == 1); //fine
     static assert(C!1 == 1); //Error: cannot alias an expression 1