5. A language processing apparatus as recited in claim 4, wherein said available parts of speech include noun and verb, and said estimate means includes means for estimating a location at which said second form is different from said first form, when said target morpheme is verb, and means for estimating a location at which said second form is different from said form when said target morpheme is noun.
5. A language processing apparatus as recited in claim 4, wherein said available parts of speech include noun and verb, and said estimate means includes means for estimating a location at which said second form is different from said first form, when said target morpheme is verb, and means for estimating a location at which said second form is different from said form when said target morpheme is noun. 6. A language processing apparatus as recited in claim 5, wherein said available parts of speech further include a phrasal expression formed of a plurality of morphemes, said phrasal expression includes a phrasal verb equivalent to a verb, and a phrasal noun equivalent to a noun, said means for positioning the input position further includes means for determining whether or not said first form is a phrasal expression, and said estimate means further includes means, when said first form is determined to be a phrasal expression, for determining whether the phrasal expression is a phrasal verb or a phrasal noun, means, when said target morpheme is a phrasal verb, for estimating a location at which said second form is different from said first form, and means for estimating, when said target morpheme is a phrasal noun, a location at which said second form is different from said first form.