A polynomial written either in ascending or descending powers of a variable is called the standard form of a polynomial.
(i) is a polynomial in standard form as the powers of x are in ascending order.
(ii) is a polynomial in standard form as the powers of y are in ascending order.
(iii) is a polynomial in standard form as the powers of x are in ascending order.
(iv) is a polynomial in standard form as the powers of t are in ascending order.