Error substituting bash for special variable

When you use bash to move sample.sh below, an error is generated with a special variable that substitutes the variable.
Probably because it is treated as a string, I don't think I can pull the arguments. Is there any way to do this?

[root@test]#cat sample.sh
#!/bin/bash

echo$2

echo${2}

N = 2
echo${$N}

[root@test] #sh sample.sh abc
B
B
sample.sh: line 8: ${$N}: incorrect substitution