Capital IQ

1) You have used .net framework version 3.5 and 4.0. What is the difference between them?
2) What is polymorphism?
3) In function overloading, return type is also part of the polymorphism?
4) So the following fns are right?
int add(int a, int b)
{
return a+b;
}

string add(int a, int b)
{
return (a+b).ToString();
}