A.含有未知函數(shù)的項(xiàng) B.含有未知函數(shù)的導(dǎo)數(shù)的項(xiàng) C.既含有未知函數(shù)又含有未知函數(shù)的導(dǎo)數(shù)的項(xiàng) D.既不含有未知函數(shù)又不含有其各階導(dǎo)數(shù)的項(xiàng)