[…] the morpheme {'ed'} has various members (/Əd/ in 'added', /t/ in 'walked', /ey/ → /u/ in 'took', etc.), and occurs after all morphemes which occur before '–ing', except 'cut'. At first blush we might try to treat it as we did the {'en'} morpheme, and to include in it a zero member which occurs after 'cut'. […] if we compare 'I missed it yesterday', 'I cut it yesterday', with 'I miss it these days', 'I cut it these days', the only indication that the zero member of {'ed'} is present after the first 'cut' and not after the second is the occurrence of 'yesterday'. In 'I cut it.' we cannot tell whether the morpheme {'ed'} is present or not, although in 'I missed it', 'I miss it', we can recognize the presence or absence of the morpheme {'ed'}. This means that we have here a many-one correspondence between our elements and the utterance, i.e. in one direction: given our elements, we can reconstruct the utterance; given {'I' } + {'cut'} + {'ed'} + {.} we construct 'I cut.', since the member of {'ed'} after {'cut'} is zero. But given 'I cut', we cannot say uniquely what elements it contains, i.e. whether or not it contains the morpheme {'ed'}.
- Harris (1951), a pag.214