present perfect simple/continuous

Is the second sentence right??

"I've been teaching 20 students all day."
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"I've taught 20 students today." => if the sentence is correct, does it mean that I was teaching each one separately? One by one?

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The second sentence does tend to suggest that it was 20 students, one by one. But it's not really clear how (or even whether) the 20 students were divided up.
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Quote:

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Originally Posted by Philly

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The second sentence does tend to suggest that it was 20 students, one by one. But it's not really clear how (or even whether) the 20 students were divided up.
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OK, thank you for your response.