What word is the verb tense in she will have been driving for 6 hours by time arrives?

The verb tense in the sentence "She will have been driving for 6 hours by the time she arrives" is future perfect progressive.

Here's why:

* Future: The sentence describes an action that will happen in the future.

* Perfect: It indicates an action that will be completed before a specific time in the future (her arrival).

* Progressive: It emphasizes the continuous nature of the action (driving) over a period of time (6 hours).