The cognitive attitude verb KNOW in most languages typically selects for a factive complement (Kiparsky and Kiparsky 1970). It is noted in the literature (Lee 1978, 1999; Kiefer 1978, Őzyildiz 2017, a.o.), however, that KNOW in some languages may take various forms of complements and that factivity varies depending on the complement types. An obvious generalization made is that nominalized complements tend to convey a factive reading, while non-nominal ones tend not to (Kastner 2015). This work makes it clear that for a clause selected by KNOW to have a factive reading, it not only bears a nominal feature but also carries a structural case. This paper additionally points out the following three issues and discusses their theoretical implications as to the syntax and semantics of attitudinal predicate constructions: (i) Cognitive attitude verbs may simultaneously take a nominalized clause and a predicational clause; (ii) The non-factive KNOW in the three languages commonly displays neg-raising and naturally anti-rogativity, siding with doxastic (belief) verbs; (iii) Lexically negated forms of these verbs select only for a nominalized (factive) clause.