How to use Structural Pseudo class in CSS3

How to use Structural Pseudo class in CSS3

nth-child

this is a first child (first-child)

this is a second child even

this is a third child odd

this is a fourth child

this is a fifth child

this is a six child

this is a seven child (last-child)

in nth-child( number) can use

in nth-child( 3in +1 ) can also use