Answer:
CONTROLLING SHIFTS IN VERB TENSE
Writing often involves telling stories. Sometimes we narrate a story as our main purpose in writing; sometimes we include brief anecdotes or hypothetical scenarios as illustrations or reference points in an essay.
Even an essay that does not explicitly tell a story involves implied time frames for the actions discussed and states described. Changes in verb tense help readers understand the temporal relationships among various narrated events. But unnecessary or inconsistent shifts in tense can cause confusion.
Generally, writers maintain one tense for the main discourse and indicate changes in time frame by changing tense relative to that primary tense, which is usually either simple past or simple present. Even apparently non-narrative writing should employ verb tenses consistently and clearly.
General guideline: Do not shift from one tense to another if the time frame for each action or state is the same.
Examples:
1. The instructor explains the diagram to students who asked questions during the lecture.
Explains is present tense, referring to a current state; asked is past, but should be present ( ask ) because the students are currently continuing to ask questions during the lecture period.
CORRECTED: The instructor explains the diagram to students who ask questions during the lecture.
2. About noon the sky darkened, a breeze sprang up, and a low rumble announces the approaching storm.
Darkened and sprang up are past tense verbs; announces is present but should be past (announced) to maintain consistency within the time frame.
CORRECTED: About noon the sky darkened, a breeze sprang up, and a low rumble announced the approaching storm.
3. Yesterday we walk to school but later rode the bus home.
Walk is present tense but should be past to maintain consistency within the time frame (yesterday); rode is past, referring to an action completed before the current time frame.
CORRECTED: Yesterday we walked to school but later rode the bus home.
General guideline: Do shift tense to indicate a change in time frame from one action or state to another.
Examples:
USING OTHER TENSES IN CONJUNCTION WITH SIMPLE TENSES
It is not always easy (or especially helpful) to try to distinguish perfect and/or progressive tenses from simple ones in isolation, for example, the difference between simple past progressive ("She was eating an apple") and present perfect progressive ("She has been eating an apple"). Distinguishing these sentences in isolation is possible, but the differences between them make clear sense only in the context of other sentences since the time-distinctions suggested by different tenses are relative to the time frame implied by the verb tenses in surrounding sentences or clauses.
Step-by-step explanation: