Should I say? If my friend say with me that "I met a friend of yours last night", so should I say "Is he a teacher? / Is he Tom" or "was he a teacher? / was he Tom?"? If my friend say with me that "There was a president in the US who freed the slaves. Who was this/that?", so should I say "He was Lincoln, wasn't he?" or "He is Lincoln, isn't he?"? Should I use the past tense or the present tense?