Sometimes it may be necessary to use several verb tenses in a single paragraph.
Once the astronauts were in orbit, they relaxed. They had not been
given a moment to think their own thoughts for several hours, and they
needed a chance to sit back and to absorb what was happening to them.
Below them the Pacific Ocean edged into view. Above them the moon looked
as distant as ever. We like to cover every detail of these space ventures
in the news, but most of us will never know what goes on in the minds
of people who are beyond the pull of their own world's gravity. What we do
know is that finally the astronauts ate their rations quietly and slept.
In the paragraph above, the verbs are in several different tenses because the writer is deliberately showing shifts of time in the events being described.
Application 5
Shifting tense without a good reason distracts a reader.
While Rosa is arguing about the bill, I walked around the table and poured everyone some more coffee.
After reading the sentence above, we guess that the events in the restaurant happened during the same time period, but the shift to past tense after the comma makes us wonder about that guess. The time shift is distracting. In any piece of writing, all verbs should be in the dominant tense unless the writer wants to shift the time for a reason that will be obvious to the reader.
Application 6