A comma marks direct address in a sentence for a slight pause and to emphasize direct address.
A comma marks direct address in a sentence by setting off the person or thing being directly spoken to. In the sentence 'Sir, I believe you left your umbrella in the taxi,' the direct address 'Sir' is separated by a comma.
Commas are used to indicate a slight pause and emphasize the direct address, helping to clarify the speaker's intended audience.
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