The simple stem is used further in the present tense: me ama vu; lo protekte nus, etc.
If we look around us in the national languages to find an expression for the past tense (the tense most often used in ordinary conversation, in narratives, etc., and for which it is therefore urgent to find an easily formed and easily used expression), we discover that the Romanic languages are of no use for our purpose, as the formation of their two preterit tenses is not uniform enough to serve as basis for an interlingual formation; the Slavic -l is not sufficiently known in the rest of Europe and in America. But fortunately we find in English, Scandinavian and Dutch an ending which is excellent for our purpose, namely -d in E lived, Dan levede, Sw levade, Dutch leevde, etc. Nor is this far from D -te. Thus from the verbs already mentioned we form the past: amad, protekted, marid, konstitud, esed, an added -e being only necessary between a consonant and the ending -d. Stress as in the infinitive.
By the side of this it is advantageous to have an analytic form for the past, and E did naturally offers itself for this purpose: me did ama, protekte etc. It should not, however, be used with the same emphatic meaning as in present-day English, but rather as often in Elizabethan English, where he did say meant nothing more than he said. Did may be added to two verbs: lo did nek ama ni estima la, and be used by itself: lo ama la, kom lo did sen unesmi marita he loves her as he did his first wife.