Normal Form Theorem (Kleene, 1943): "Given a partial recursive function (X1,...,xn), there is a number e such that $(x1, ..., xv) = U(uy T (, X2, ..., Xpy)), Select all the true statements regarding Kleene's normal form theorem: U can be considered as a form of decoding function Every recursive functions can be attributed a unique encoding number e U can be considered as a form of encoding function OuyTn (e, X1, Xn, y) is a primitive recursive function The value of uyTn (e, X1, Xmy) is a natural number. For all function , the value of uyt, (e, X1, ... Xny) is defined uyTn (e, X1, ..., Xn, y) can be considered as a form of decoding function U is a primitive recursive predicate U is a primitive recursive function Every primitive recursive functions can be attributed a unique encoding number e Ouyan (e, x1, Xn, y) can be considered as a form of encoding function Tn is a primitive recursive predicate