a = get_string('QUESTION HERE.','')
//The list of codes (Name of Password can be anything. Make sure that the "if a = ???" is the same as the of the passwords.
Name of Password 1 = 'Password'
Name of Password 2 = 'Password'
Name of Password 3 = 'Password'

//What to do if password is correct
if a = Name of Password 1
{
ACTION HERE
}

else

if a = Name of Password 2
{
ACTION HERE
}

else

if a = Name of Password 3
{
ACTION HERE
}