#include using namespace std; int t; double u; //Line 1 //Line 2 //Line 3 namespace expN { int x; char t; double u; } //Line 4 //Line 5 //Line 6 using namespace expN; int main() { int one; double t; double three; //Line 7 //Line 8 //Line 9 } To refer to the variable u (that is declared in line 6) inside the main we write