Dolphins can swim at speeds exceeding 20 mph while expending remarkably little energy compared to other marine animals. Marine biologists...

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

• Sentence 1:
  • Dolphins can swim at speeds exceeding 20 mph
    • while expending remarkably little energy
      • compared to other marine animals.
• Sentence 2:
  • Marine biologists have now determined
    • how [?do] dolphins achieve such impressive efficiency[?.]
• Sentence 3:
  • The dolphins' skin contains specialized structures
    • that reduce turbulent drag
      • through microscopic surface adjustments.

Understanding the Meaning

Let's start reading from the beginning:

The first sentence tells us about dolphins:

• They can swim at speeds exceeding 20 mph
• While doing this, they expend remarkably little energy
  • compared to other marine animals

So dolphins are exceptionally efficient swimmers.

Now the second sentence:

• "Marine biologists have now determined how _____"

This is where we have the blank. Let's look at the choices:

• Choices A and C include "do"
• Choices B and D don't include "do"
• Choices A and B end with a period
• Choices C and D end with a question mark

To see what works here, let's read the complete phrase and understand what it's saying!

The complete phrase reads: "how dolphins achieve such impressive efficiency"

Now let's understand what this structure is telling us:

• "Marine biologists have now determined..."
  • This is making a STATEMENT - the biologists figured something out
  • What did they determine? → The next part tells us
• "how dolphins achieve such impressive efficiency"
  • This is what they determined
  • It's a question concept ("how do dolphins do it?"))
  • BUT it's embedded INSIDE the statement
  • It's not asking a question - it's stating what was discovered

What do we notice about the structure here?

• When a question is embedded within a statement, it's called an indirect question
  • The question becomes part of a larger statement
  • It functions as the object of the verb "determined"
• Compare these two:
  • Direct question: "How DO dolphins achieve this?"
    • This is asking a question directly
    • Uses question word order: "do" comes before "dolphins"
    • Ends with a question mark
  • Indirect question: "Scientists determined how dolphins achieve this."
    • This is stating what was discovered
    • Uses statement word order: "dolphins" comes before "achieve"
    • No "do" needed
    • Ends with a period (because the whole sentence is a statement)
• Our sentence is making a statement about what marine biologists determined
  • Even though WHAT they determined involves a "how" question
  • The overall sentence structure is a statement, not a question

So we need:

• Statement word order: "dolphins achieve" (not "do dolphins achieve")
• Period ending: because the sentence is making a statement

The correct answer is B: "dolphins achieve such impressive efficiency."

The final sentence explains the answer: "The dolphins' skin contains specialized structures that reduce turbulent drag through microscopic surface adjustments." This is HOW they achieve such efficiency - through their specialized skin.

GRAMMAR CONCEPT APPLIED

Indirect Questions Within Statements

When a question is embedded within a larger statement (called an indirect question in grammar terms), it uses statement word order and follows the punctuation of the main sentence, NOT question structure.

Pattern for Direct Questions:

• Structure: Question word + auxiliary verb + subject + main verb + ?
• Example: "How DO dolphins swim so fast?"
• Features: Question word order (auxiliary "do" before subject), question mark

Pattern for Indirect Questions:

• Structure: [Statement] + question word + subject + verb + [statement punctuation]
• Example: "Scientists discovered how dolphins swim so fast."
• Features: Statement word order (no auxiliary "do"), period ending

Why the difference?

• In a direct question, you're ASKING the question
• In an indirect question, you're STATING what someone discovered, wondered, determined, asked, etc.
• The embedded question functions as a noun - it's the object of verbs like "determined," "discovered," "wondered," "asked," "explained"

Application to this question:

• Direct: "How DO dolphins achieve such impressive efficiency?" (asking)
• Indirect: "Marine biologists have now determined how dolphins achieve such impressive efficiency." (stating what was determined)

The question word "how" stays, but the structure shifts from question form to statement form because it's now embedded within a larger declarative sentence.