A day is the 24-hour period during which Earth completes one rotation on its axis.
(A day; is; the 24-hour period during which Earth completes one rotation on its axis) (Earth; completes; one rotation on its axis; T:the 24-hour period)
A day Earth
is completes
the 24-hour period during which Earth completes one rotation on its axis
one rotation on its axis T:the 24-hour period