Verb tense consistency on the sentence level
Do not change tenses when there is no time change for the
Since there is no indication that the actions happened apart from one another., there is no reason to shift the tense of the second verb.
Note another example.
The above sentence means that Mary walks into a room at times. The action is habitual present. The second action happens when the first one does. Therefore, the second verb should be present as well.
Change tense only when
there is a need to do so.
Usually, the timing of actions within a sentence will dictate when the tense must change.
The first action will take place in the future; therefore, the second one will as well.
CORRECT: The second action took place in the past; the first action occurred before the past action. Therefore, the first action requires the past perfect tense (had + verb).
Verb tense consistency on the paragraph level
All actions in the above paragraph happen in the present except for the
future possibility dependent upon a
present action taking place: " If a cat sees the bird, the cat will kill it."
PAST TENSE PARAGRAPH
All of the actions in
the above paragraph happen in the past except for the possibility dependent upon
one action taking place: "If a cat saw the bird, the cat would kill it."