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Which is more effective in telling the story about the company's past performance in a field: "the company has been providing services since 1999" or "the company has provided services since 1999"
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The first is slightly friendlier.
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Contractor has provided response to each point with evidence to the recommendations given in Company’s letter

I feel that past tense tone is stronger with "has provided" versus "has been providing" as "providing" has more of a present tense tone and when you preface with "has been" tends to mix the tense IMHO