Different between had checked and have checked?
“Had checked” is the Past Perfect tense and is used to say something happened before another action in the past. Example: “I had checked the drawings before I gave them to the teacher.” Action 1, checked the drawings; Action 2, gave them to the teacher. (Had + Past Participle) “Have checked” is the Present Perfect tense and is used to talk about something in the past, but the time is not specific. If you are specific about time, eg yesterday, last week, Monday etc, then you have to use the Past Simple tense. Example: “I checked the drawings last Monday.” Specific time in the past. “I have checked the drawings.” This is in the past but the actual time isn’t important so it isn’t specified. (Have/Has + Past participle) Grammar helps you be specific about time. Hope this helps you.