Normally we would say "I missed dinner" , meaning that I did not go to dinner. "I lost my dinner", suggests that I was carrying it in a bag or something, or lost it. Or perhaps I became sick and upchuked. Duolingo is a fine program up to about this level (so call present perfect), but not the translations do not make sense, or they are very questionable. For example, this exercise is supposed to be on the present perfect - but almost everything is translated as the the past tense There is a significant difference in meaning in English between, for example, "I went there" and "I have been there," or, in this case, "I missed my dinner" or I have missed my dinner".