Picnic Past simple - Only with definite time expressions? No, you can also use it on its own (with no expressions of time).
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PicnicPast simple - Only with definite time expressions?No, you can also use it on its own (with no expressions of time).
Picnicpresent perfect does not require definite time expression;Past simple does not require a definite time expression either. No tense in English requires a definite time expression.
PicnicPast simple - Only with definite time expressions?No. You have it backwards.
Picnicbut when I want to talk about something that happened in the past, but I don't remember when, I would not write with definite time expression and not in the present perfect form because it does not relate to present.I have no idea what the point of confusion seems to be. The posts above have already answered your question, but maybe the chart below wil