Consider the following program segment

program main;

Var A,B,C: real;

procedure S1( A: real);

Var D: real;

begin S1;

call S2 (B);

statement1

end S1;

procedure S2( C: real);

Var D, B: real;

begin S2;

statement2

end S2;

begin main;

call S1(A);

end main

1. Give the run time representation of main
2. Give the referencing environment for S1.
3. Assuming static scope, give the implementation of the referencing environment at statement1
4. Assuming dynamic scope, give the implementation of the referencing environment at statement2