I know he's a fool. — NOT: Robert knows Mary is ill.
Comment:
The COMP /ki/ can be described as "optional" in these examples but the probability of the presence or absence of /ki/ is closely related to the Mauritian Creole stress system, a subject not, alas, covered by APiCS. The acute is used above to mark the vowels of stressed syllables. Essentially the more unstressed syllables there are between the stressed syllable of the verb kóne 'know' and the first stressed syllable which follows, the more likely it is that /ki/ will not occur.