While constructing the Limyra Bridge, ancient Roman builders relied on temporary wooden beams to support the stone and brick structure....

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

• While constructing the Limyra Bridge,
• ancient Roman builders relied on temporary wooden beams
  • to support the stone and brick structure.
• These temporary supports,
  • a construction system known as falsework [?],
  were removed
  • when the bridge was completed.

Understanding the Meaning

The first sentence tells us:

• While building the Limyra Bridge,
• ancient Roman builders used temporary wooden beams
  • to hold up the stone and brick structure as they built it.

Now the second sentence:

• "These temporary supports"
  • refers back to those wooden beams mentioned in the first sentence
• Then we get additional information:
  • "a construction system known as falsework"
  • This phrase is telling us what these temporary supports are called
    • it's giving us the technical name for them

This is where we have the blank.

Let's look at the choices - they all have "falsework" but differ in what punctuation (if any) comes after it.

To see what works here, let's read the rest of the sentence:

• "were removed when the bridge was completed"

Now let's understand what this is telling us:

The complete sentence structure is:

• Subject: "These temporary supports"
• Descriptive phrase inserted in the middle: "a construction system known as falsework"
  • This phrase renames/describes what the supports are
• Main verb: "were removed"
• Additional detail: "when the bridge was completed"

What do we notice about the structure here?

• The phrase "a construction system known as falsework" is inserted between the subject and its verb
  • It starts after "supports" with a comma
  • It's extra descriptive information dropped into the middle of the sentence
  • After this inserted phrase, the sentence needs to continue back to the main structure (the verb "were removed")
• When you insert a descriptive phrase in the middle of a sentence, you need commas on both sides
  • The comma before it signals: "here comes some extra information"
  • The comma after it signals: "okay, back to the main sentence now"

So we need a comma after "falsework" to close off this inserted phrase before returning to the main verb.

The correct answer is C. falsework,

GRAMMAR CONCEPT APPLIED

Using Commas to Set Off Inserted Descriptive Phrases

When you insert extra descriptive information in the middle of a sentence, you need to use commas on both sides of that phrase (called an appositive in grammar terms) to show where the insertion begins and ends:

Pattern:

• Main sentence structure: Subject + Verb
• With insertion: Subject, [descriptive phrase], Verb

Example 1:

• Without insertion: "The scientists announced their findings."
• With insertion: "The scientists, a team from Harvard, announced their findings."
• "a team from Harvard" = inserted descriptive phrase
• Comma before AND after the phrase

Example 2:

• Without insertion: "My neighbor moved to Seattle."
• With insertion: "My neighbor, a retired teacher, moved to Seattle."
• "a retired teacher" = inserted descriptive phrase
• Comma before AND after the phrase

In this question:

• Main structure: "These temporary supports... were removed"
• Inserted phrase: "a construction system known as falsework"
• The phrase already has a comma before it, so we need a comma after it to complete the pair
• Result: "These temporary supports, a construction system known as falsework, were removed"

The key principle: If you open with a comma, you must close with a comma before returning to the main sentence.