1
$-\overset{N}{\mathop{\overset{||}{\mathop{C}}\,}}\,-O-$
✓
✗
2
$-\overset{C}{\mathop{\overset{||}{\mathop{N}}\,}}\,-O-$
✓
✗
3
$-\overset{O}{\mathop{\overset{||}{\mathop{C}}\,}}\,-\underset{|}{\mathop{N}}\,-$
✓
✗
4
$-\overset{C}{\mathop{\overset{||}{\mathop{O}}\,}}\,-\underset{|}{\mathop{N}}\,-$
✓
✗