The passage below describes the scientific investigation of the 1908 Tunguska event. Which form of the verb 'elapse' correctly completes the sentence to conform to the conventions of Standard English?
Cevap:In 1908, a massive explosion occurred near the Podkamennaya Tunguska River in Russia, flattening millions of trees. Because the region was extremely remote and politically unstable, scientific research was delayed for years. By the time the first scientific expedition finally reached the site in 1927, nearly two decades 【had elapsed】 since the event, leaving researchers to study decaying tree trunks rather than fresh evidence.
Cevap
had elapsed
The sentence establishes a timeline where the elapsing of two decades occurred before another past event (the first scientific expedition reaching the site in 1927). Therefore, the past perfect tense 'had elapsed' is required to show that one past action was completed prior to another past action.
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Using the past perfect tense ('had' + past participle) to describe an action that was completed before another action in the past.
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