Letters that make imperfective aspect
s, a, e, f, p, c, m, r, t, i, v are letters that make 'imperfective aspect'
Words within imperfective aspect
ER, aspect, RF, spec, pe, ti, EC, MP, perfective, perfective aspect, imperfective, perfect, imperfect, iv, as, ECT, CT, IV, asp, AS, imp, As, Er, Fe, Rf, Ti are words within 'imperfective aspect'