For each of the following functions enter "E" to indicate that the function is even, "O" to indicate it is odd, and "N" to indicate that is neither even nor odd.

$f(x) = \sin^2 x$.
$f(x) = \sin x^2$.
$f(x) = \sin(\cos x)$.
$f(x) = \sin(\sin x)$.
$f(x) = \sin x + \cos x.$