The journals from the Arctic expedition of 1923 _______ considered invaluable primary sources for understanding early polar exploration.

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

• The journals
• from the Arctic expedition of 1923
• [?] considered invaluable primary sources
• for understanding early polar exploration.

Understanding the Meaning

This sentence is about some historical documents:

• 'The journals from the Arctic expedition of 1923'

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

• 'The journals ______ considered invaluable primary sources...'

Let's look at our choices:

• A. are (plural)
• B. has been (singular)
• C. is (singular)
• D. was (singular)

So we're deciding between singular and plural verb forms.

What's the subject of this sentence?

• 'The journals' - this is plural (more than one journal)
• The phrase 'from the Arctic expedition of 1923' is just describing which journals we're talking about

Here's what we notice:

• The subject is 'The journals' (plural)
• We need a verb that matches this plural subject
• Even though 'expedition' (singular) appears between the subject and the blank, it's just part of a describing phrase - it doesn't change what the verb needs to match

So we need: are (the plural form)

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

• '...are considered invaluable primary sources for understanding early polar exploration'
• This is saying that today, scholars view these journals as extremely valuable historical documents for learning about early polar exploration
• Present tense ('are') makes sense because we're stating a current fact about how these journals are regarded now

The correct answer is A: are

GRAMMAR CONCEPT APPLIED

Subject-Verb Agreement with Intervening Phrases

When a describing phrase comes between the subject and the verb, the verb must still agree with the actual subject, not with nouns in the describing phrase:

Pattern:

• Subject (plural/singular) + describing phrase + verb (must match subject)

Examples:

1. The books on the shelf are new.
   • Subject: "books" (plural)
   • Describing phrase: "on the shelf"
   • Verb: "are" (plural) - matches "books," not "shelf"
2. The scientist from the top universities is speaking today.
   • Subject: "scientist" (singular)
   • Describing phrase: "from the top universities"
   • Verb: "is" (singular) - matches "scientist," not "universities"
3. The results of the experiment were surprising.
   • Subject: "results" (plural)
   • Describing phrase: "of the experiment"
   • Verb: "were" (plural) - matches "results," not "experiment"

In our question:

• Subject: "The journals" (plural)
• Describing phrase: "from the Arctic expedition of 1923"
• Verb needed: "are" (plural) - matches "journals," not "expedition"

The key is to identify the true subject and make sure your verb agrees with it, even when other nouns appear between them.