Read the passage about Marie Curie's pioneering scientific work. What is the correct form of the verb 'conduct' that fills the blank to maintain a logical and consistent sequence of verb tenses in the passage?
Cevap:By the time Marie Curie discovered radium in 1898, she 【had conducted】 years of painstaking research on uranium rays in a poorly ventilated shed.
Cevap
had conducted (or had been conducting)
The correct answer is 'had conducted' (or 'had been conducting') because the introductory clause 'By the time Marie Curie discovered radium in 1898' establishes a past reference point. The action of performing research happened prior to this discovery, which grammatically requires the past perfect tense to maintain a logical and consistent sequence of events.
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Anahtar Kavram
Using the past perfect tense to show an action completed before another past event.