Abstract
In some cases a predicate formed by a copulative verb být (to be) and a noun in nominative case may be expressed in two different agreement forms in past tense: that is either with the noun in position of a subject (Ten film byl pohádka), or with the noun forming a verbo-nominal predicate (Ten film byla pohádka). For an easier distinction of the grammar role of these nouns, especially in scholarly and journalistic texts, a noun in nominative case represents a subject and a noun in instrumental case represents a predicative noun.
References
Grepl M., Karlík P., 1986, Skladba spisovné češtiny, Praha: Státní pedagogické nakladatelství.
Hrdlička M., 2011, Nominativ, [in:] J. Hasil, M. Hrdlička (eds.), Psáno do oblak, Praha: Karolinum, s. 299–305.