Add just one word to your English dictionary and you have to write a rule that shows what that word translates to in each of the other n-1 languages. A universal language. In interlingual systems, translation occurs in only two phases. Analysis produces an interlingual form for the source sentence and this is then expressed by the synthesizer. We just define its meaning.
Tenses are the ways a language expresses the past, present, and future.
The problem for machine translation is that languages can have quite different sets of tenses. Compare French and English. A transfer system would require lots of complex rules to show which English tense is the equivalent of a French present-tense verb form. But step away from the idea of tenses and think in terms of time. S is the time when the sentence is spoken, E is the time of the event spoken about, and R is a reference time.