Tense, Voice, and Mood Shifts

You can/cannot change from one mood to another in the same passage, essay, or research paper.

Which is the correct example?

You can/cannot shift from one verb tense to another (i.e. present to past) in a single sentence

The ____ shows the author’s attitude and intentions for writing the passage in the first place.

The first of the finishers wins/win/winning a special prize.

Which term means to: inform the reader who is talking.

Because we had already eaten breakfast, Charlie Was/is being/will be forced to eat alone.

When the bridge closed last week, our commute was/had been/will be disrupted