Doubts about Present Perfect Tense Should I use Present Perfect Tense when I talk about something in the past, but I don't explain when it happened? For example: "They didn't have dinner with us." in this case I didn't say when it happened, so should I use Present Perfect Tense: "They haven't dinner with us."? Thanks for anyone who help me, and I'm sorry for my English, I need improve it a lot yet