Question 235·Easy·Form, Structure, and Sense
In 1836, the author completed a travel journal describing regions of the Amazon Rainforest that scientists ______ only briefly before that time.
Which choice completes the text so that it conforms to the conventions of Standard English?
For verb tense questions, first underline all time clues (years, phrases like "before that time," "now," "by then"). Then decide the timeline: which action happened first, and which is the reference time? If one past event clearly happened before another past time, look for a tense that marks an earlier completed past action (often the past perfect). Quickly eliminate choices that use present or present-perfect tenses when the sentence is locked in the past, and avoid progressive forms unless the sentence emphasizes an action being in progress at that specific time.
Hints
Look at the time phrases
Pay close attention to "In 1836" and "before that time". What do these phrases tell you about when each action happened?
Compare the two actions
Which happened first: the scientists exploring the regions, or the author completing the travel journal? Think about how English shows that one past action came before another past action.
Match the tense to the timeline
You need a verb form that clearly shows an action that was already finished by a certain point in the past. Which choice does that best, instead of talking about the present or an ongoing past action?
Step-by-step Explanation
Understand the timeline in the sentence
Identify the time clues: the sentence starts with "In 1836", and later says "before that time". This tells you:
- One action is the author completing a travel journal in 1836.
- The other action is the scientists briefly exploring the regions before 1836. So the scientists’ exploration happened first, and the author’s journal came later, but both are in the past.
Decide what kind of tense is needed
When English shows two past events, and one happened earlier than the other, we usually use a verb form that clearly marks the earlier past action.
- The journal completion is the main past time (1836).
- The scientists’ exploration must be shown as already completed by that past time. So we want a verb tense that means: "this was finished before that past time."
Test each answer choice against the timeline and meaning
Check each option in the blank:
- A) explore → present tense. This does not fit with the clear past time "In 1836" and "before that time".
- C) have explored → present perfect. This connects past actions to now, but the sentence is anchored in 1836, not the present.
- D) were exploring → past progressive. This suggests the scientists were in the middle of exploring around that time, not that they had already finished before 1836. Only one remaining option clearly shows that the exploration was completed before 1836.
Choose the verb that shows an earlier completed past action
The verb form that shows an action finished before another past time is the past perfect. That is exactly what "had explored" does: it shows that scientists had already explored the regions (briefly) before the author completed the journal in 1836.
So the correct answer is B) had explored.