have prepared vs prepared

past tense Vs present perfect tense

I prepared the report. - A past tense verb 'prepared' is used to show that the action happened in the past.

I have prepared the report. - A present perfect tense verb 'have prepared' is used to show that the action happened in the past and was completed before the present moment of writing or speaking the sentence.

Both can be used in a letter. Which one to use depends on which of the above situation applies.
Examples:
I prepared the report before going out for a drink last night.
I have prepared the report specially for this review meeting.

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I prepared the report
我準備左份報告

I have prepared the report
我已經準備左份報告

兩者其實都係過去式,但係第二句比第一句更加肯定.
而且用法上以have+p.p是更加確切.

但係一般書信會以I prepared the report為先

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