Question 94·Easy·Boundaries
Ancient Roman concrete structures have stood for millennia. Why _____ Researchers have discovered that the material contained self-healing minerals that filled cracks over time.
Which choice completes the text so that it conforms to the conventions of Standard English?
For Standard English convention questions that involve sentence boundaries and punctuation, always read the sentence before and after the blank together. Identify whether the structure calls for a statement or a question (clues like starting with “Why,” “How,” or “Did” often signal questions), then check that the choice uses appropriate word order for that type of sentence and ends with matching punctuation. Eliminate any option where the tone or punctuation (period, question mark, exclamation point) does not fit the structure and context.
Hints
Look at the word that starts the second sentence
The second sentence begins with "Why." What kind of sentence usually starts with "Why" in English?
Think about the punctuation
Since the sentence beginning with "Why" is asking something, what punctuation mark should it end with? Check each choice’s ending punctuation.
Check the order of the words in a question
In a question about the past, where does the helping verb like "did" usually go in relation to the subject (for example, in "Why did she leave?" versus "Why she left?" )?
Match both structure and punctuation
You need the option that both uses proper question word order and ends with the correct punctuation for a question.
Step-by-step Explanation
Understand how the blank fits into the sentence
Read the full text and imagine the blank filled in:
"Ancient Roman concrete structures have stood for millennia. Why _____ Researchers have discovered that the material contained self-healing minerals that filled cracks over time."
The blank is the end of a sentence that begins with "Why" and comes right before a new sentence starting with "Researchers." So whatever you choose must complete a full sentence and have correct ending punctuation.
Recognize the sentence type starting with “Why”
Sentences that start with "Why" are usually direct questions, like "Why is the sky blue?" or "Why did she leave?" This means the second sentence here is also a direct question about the first sentence (why the structures lasted so long), so it should:
- Use question word order (helping verb before subject), and
- End with a question mark.
Check punctuation at the end of each choice
Look at the punctuation marks at the end of the options:
- Some end with a period.
- One ends with an exclamation point.
- Some end with a question mark.
Because this is a direct question that starts with "Why," it must end with a question mark, not a period or an exclamation point.
Check word order inside the question
For English questions in the past tense, we use "did" before the subject: for example, "Why did they leave?" not "Why they left?"
So in the blank, you want the helping verb before the subject ("did they"), not subject before verb ("they lasted"). Combine this with the need for a question mark to select the only option that has both the correct word order for a question and the correct ending punctuation.
The correct choice is: did they last so long?