Polish and Russian had an important influence on the emerging Modern Czech Standard Language in the first decades of the 19th century. This does not only concern vocabulary, but also morphosyntactic devices.
At the beginning of the century, an active past participle in -(v)ší and new modal predicatives as nutno, dlužno were built on Russian patterns. Genitive and instrumental cases extended their functions.
At the same time passives with- out copulae or even active constructions in -no / -to with accusative object gained a certain popularity in written Czech. These are built on a Polish pattern.
In translations from Polish, Polish-like modal predicatives as volno or možná can be found. All in all it seems that Polish had a more prominent practical position for the activists of Czech national awakening, there are more loans in the vocabulary from Polish, more Polish books were read and translated than Russian ones.
At the same time the prestige of Russian seems to have been higher, more bookish syntactic patterns are borrowed from it and some of them even survive to a certain extent until today.