Dr. Elena Rodriguez of the Scripps Institute _____ a pioneering researcher in marine biology during the 1990s. Her groundbreaking studies...

Let's begin by understanding the meaning of this sentence. We'll use our understanding of pause points and segment the sentence as shown - understanding and assimilating the meaning of each segment bit by bit!

Sentence Structure

• Dr. Elena Rodriguez of the Scripps Institute
  • [?]
  • a pioneering researcher in marine biology during the 1990s.
• Her groundbreaking studies on coral reef ecosystems
  • contributed
    • significantly to modern conservation efforts
  • and
  • helped
    • establish new protocols
      • for protecting endangered marine habitats.

Understanding the Meaning

The passage introduces us to a person:

• Dr. Elena Rodriguez of the Scripps Institute

Now here's where we need to fill in the blank:

• Dr. Elena Rodriguez _____ a pioneering researcher in marine biology during the 1990s.

Let's look at our choices:

• were (plural, past)
• have been (present perfect)
• are (present)
• was (singular, past)

What do we notice?

Subject and number:

• The subject is "Dr. Elena Rodriguez" – one person, so we need a singular verb
• "Of the Scripps Institute" is just a descriptive phrase telling us where she's from; it doesn't affect whether we use singular or plural

Time period:

• The sentence says "during the 1990s"
• This is a specific time period in the past that's completed
• We need a past tense verb to match this time marker

So we need: was (singular to match Dr. Rodriguez, past to match the 1990s)

Now let's read the rest to see the complete picture:

The second sentence tells us:

• Her groundbreaking studies on coral reef ecosystems contributed significantly to modern conservation efforts
• And helped establish new protocols for protecting endangered marine habitats

This confirms we're talking about her past accomplishments. The verbs "contributed" and "helped" are both past tense, supporting that we're describing her role during that specific time period in the 1990s.

GRAMMAR CONCEPT APPLIED

Matching Verbs to Subjects and Time Markers

When you have a linking verb (like forms of "to be"), it needs to do two things:

1. Match the subject in number:
   • Singular subject → singular verb
   • "Dr. Rodriguez was a researcher" (singular)
   • "The researchers were pioneers" (plural)
2. Match the time period being described:
   • For specific completed past time periods (like "during the 1990s," "in 2010," "last year"), use simple past tense
   • "She was a researcher during the 1990s" (correct)
   • "She is a researcher during the 1990s" (incorrect - tense doesn't match time marker)
   • "She have been a researcher during the 1990s" (incorrect - present perfect doesn't work with specific completed past times)

In this question:

• Subject: Dr. Elena Rodriguez (singular) → need singular verb
• Time marker: during the 1990s (specific past period) → need past tense
• Answer: was (singular, past)

Important note about prepositional phrases:

• Don't let phrases like "of the Scripps Institute" distract you from the true subject
• The verb agrees with "Dr. Rodriguez," not with any noun in the prepositional phrase