Drag the correct verb forms to help the exhausted detective finish his stakeout report for the chief.

If the suspect doesn't show up by midnight, we will have been sitting in this freezing unmarked van for twelve hours. At that point, my partner will have been complaining about his cold feet for exactly eleven of those hours!

If the suspect doesn't show up by midnight, we will have been sitting in this freezing unmarked van for twelve hours.

The future perfect continuous is required here because we are calculating the duration of an ongoing action ("for twelve hours") up to a specific future moment ("by midnight"). "Will be sitting" describes an action happening at a future time, but fails to capture the accumulated duration.

At that point, my partner will have been complaining about his cold feet for exactly eleven of those hours!

Because "complaining" is an ongoing, continuous action rather than a single completed event, the continuous form (will have been complaining) is much more natural and accurate here than the simple perfect (will have complained).