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Complete the mother's frantic text message to her sister about their upcoming family road trip.
Tell me honestly, how long _____________________________________ at the campsite by the time our RV finally _________________________? Assuming we don't get lost again, we ____________________________________ these dusty backroads for at least ten hours!
will you have been waiting / arrives / will have been navigating
Blank 1 & 3: We use the Future Perfect Continuous to ask about or state the duration of an ongoing action up to a future point in time. Wait and navigate are continuous actions that emphasize the exhausting passage of time.
Blank 2: In future time clauses starting with words like by the time, when, or as soon as, we use the Present Simple (arrives), not the future tense (will arrive).