"They will have been talking for over an hour by the time Thomas arrives"

Whenever you decide to use this tense, must you always include a duration that indicates how long something has been happening up to another point in time? Or is it possible to leave it out?

Thank you

It's usually included, but not always. Do you know about these usages?

eg explaining a future physical or mental state When you arrive, I'll need a shower. I'll have been working hard in the garden.

eg logical deduction / speculation Look at all the bags she is carrying. She'll have been shopping.

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No, I don't. Thanks though
Hi Clive.

I think for the logical deduction future continuous can be used.

Ex. She will be shopping.

Am I right?


Yes, that's OK in a context like 'What will she be doing tomorrow afternoon?

But in my example, the shopping was finished. She was seen while on her way home with the bags.

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