The single morpheme -ed/-enof the English past/passive

The cross-linguistic homes of Mood and Tense

“…The answer is because this V have must occur with a participle with the separate morphology of -en, a morpheme which when active spells out Past, i.e. [+T]; for arguments to this effect, see Emonds (2012 Realis future with going to are close to synonymous; it is next to impossible to find contexts where one is well-formed and/or appropriate and the other is clearly not (though nuances may differ). We conclude then that the two LFs of futures in both languages are the same, and that the difference in (otherwise unmarked) Mood values [±M] combined with [-T] is nearly meaningless.…”