The rule as to this construction is given on page 698 ; to that should be added that where the Continuative Form is used it appears on the second Verb. In Dissyllables only the final a of the stem becomes i, and when the Continuous Form Suffix is added, it is -nge (as that applied in the Perfect). In verbs of three or more syllables the final a of the stem is unchanged, and the suffix is -nga.