Question 139·Easy·Boundaries
The conference ____ once a bustling train station, now hosts art fairs and community markets every weekend.
Which choice completes the text so that it conforms to the conventions of Standard English?
For punctuation-boundary questions, first strip the sentence down to its main subject and verb to see what the core sentence is. Then decide whether the words around the blank form extra (nonessential) information or a new complete clause. Use that decision to choose punctuation: commas or paired dashes for extra information, and semicolons/colons only when there is a complete sentence before the mark and the rules for those marks are clearly met. Always check that the remaining main sentence is grammatically correct after you remove the extra phrase.
Hints
Find the main sentence
Ignore the phrase "once a bustling train station" for a moment. What is the basic sentence if you remove those words entirely?
Decide what the middle phrase is doing
Is "once a bustling train station" the main action, or is it extra information describing "the conference center"?
Think about paired punctuation
When you insert extra descriptive information into the middle of a sentence, what kind of punctuation usually appears on both sides of that information?
Check requirements for stronger punctuation
Semicolons and colons have specific rules. Do you have a complete sentence (subject + verb) immediately before the blank that could stand alone?
Step-by-step Explanation
Understand the sentence structure
Read the whole sentence with each option in mind:
"The conference ____ once a bustling train station, now hosts art fairs and community markets every weekend."
The main idea is that the conference center now hosts events, and "once a bustling train station" is extra descriptive information about the conference center.
Identify the type of phrase after the blank
The words "once a bustling train station" rename or describe the conference center. This is an interrupting, nonessential (extra) description, not the main subject or verb of the sentence.
So the structure is:
- Main subject: "The conference center"
- Extra description: "once a bustling train station"
- Main verb and rest of sentence: "now hosts art fairs and community markets every weekend."
Match the punctuation to the structure
Nonessential (extra) phrases in the middle of a sentence are usually set off by a matching pair of punctuation marks: either commas or dashes.
You already have a comma after "station," so the mark in the blank must work with that comma to set off the descriptive phrase correctly and still leave a clear main sentence.
Test each option against grammar rules
Check each option:
- "center," would pair with the existing comma after "station" to neatly set off the extra phrase: "The conference center, once a bustling train station, now hosts ..." This leaves a complete main sentence: "The conference center now hosts art fairs and community markets every weekend."
- "center—" would need another dash after "station" (not a comma) to be consistent.
- "center;" requires a complete sentence on both sides, which you don't have before the blank.
- "center:" must come after a complete sentence and introduce an explanation or list, which also doesn’t fit here.
Therefore, the correct choice is "center,".