Complex sentence: Note the archaic use of the instructive case of the third infinitive--a common error, even for native Finns, is to confuse this with the illative case,'tappamaan', which would be incorrect.
Split into simpler sentences: Note the archaic use of the instructive case of the third infinitive. A common error, even for native Finns, is to confuse this with the illative case,'tappamaan', which would be incorrect.