A verb tense question tests whether you can tell when something happens. Find the subject and check that each form fits it, then look for a time clue. Without a date, trace the order of events and read nearby verbs. Present forms describe now, simple past forms tell finished past events, has forms link past to now, and would can look ahead from the past. Each tense needs support from the text, not a guess about the person.
Hints
- Hint 1
Look at the time words at both ends of the sentence. Which event does each one describe?
- Hint 2
Check the timing of Franklin’s work. How does the sentence place it in relation to the skepticism and the later scientists’ work?
Step-by-step
Test the time clues
Step 1Check what changes
Start with British chemist Rosalind Franklin, the person doing the refining. Every choice fits that one person, so the difference is time, not whether the verb fits the subject. What tells us when the work happens? We need to read the surrounding words to see how the sentence places her work in time.
- Step 2
Test what the time words tell us
The sentence gives us early skepticism from her peers and enabling later scientists to visualize. What do those clues tell us about Franklin’s work? The sentence reports her work as a past achievement, with skepticism early on and other scientists using the technique later. Her work is presented as a completed event, and its results helped scientists who came afterward. We don't need an exact date to understand that order.
- Step 3
Choose the tense for the report of past work
Which form reports that completed achievement directly? The simple past does this, so refined fits the sentence. Would refine would need the narrator to look ahead to her achievement from an earlier point in the past. The phrase later scientists tells us who benefited afterward; it doesn't put the narrator at that earlier point. The sentence reports what Franklin did, rather than looking ahead to what she would do. Choice D.