Fortunately, the accusative case differs from the nominative only in one key place: masculine singular nouns. For feminine (die), neuter (das), and plural (die) nouns, articles remain the same in both ...

Case theory deals with a special property that all noun phrases are assumed to have. If they lack this feature, the sentence which contains the phrase is rendered ungrammatical. It is a theory of the ...

Note that the only words that change their form in the accusative case are the masculine words, ie the der words. All the other forms are the same as the nominative case.