In 1928, Scottish researcher Alexander Fleming accidentally discovered penicillin, which became the world's first effective antibiotic. Since Fleming's historic breakthrough, medical researchers ______ countless other antibiotics to treat bacterial infections, saving millions of lives and fundamentally transforming modern healthcare.
Which choice completes the text so that it conforms to the conventions of Standard English?
- have developedCevap
- Bdeveloped
- Chad developed
- Dwill develop
Cevap
The present perfect tense 'have developed' is correct because the word 'since' indicates an action that began in the past and continues to be relevant in the present.
The correct answer is the phrase 'have developed' because the sentence establishes a time frame starting in the past and extending to the present with the prepositional phrase 'Since Fleming's historic breakthrough'. This requires the present perfect tense. Because the subject 'medical researchers' is plural, the plural auxiliary verb 'have' must be used.
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Using the present perfect tense with the time marker 'since'
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