A punctuation question with a description in the middle tests how you set extra information apart from the main sentence. Read around the blank to find the subject and its verb, who or what the sentence is about and what it does. Then remove the description to check whether the sentence still works. Commas or dashes must come in matching pairs around removable information in the middle. Semicolons can join two complete sentences.
Hints
- Hint 1
Look at the words immediately after the blank. Which word tells what the wood did?
- Hint 2
Read the sentence without the disk description. If it still works, what punctuation rule applies to that description's two ends?
Step-by-step
Find the insert and match its marks
Step 1Find the main sentence
Read from One wood to revealed, the word right after the blank. What did the wood sample do? It revealed narrow rings, so revealed is the main verb, the word that tells what the sample did. The punctuation needs to keep the sample and its main verb in one sentence.
- Step 2
Cross out the description
Can we remove a thin disk cut from the trunk without breaking the sentence? Without it, one wood sample revealed years of narrow rings, which still forms a full sentence. So the disk description is an insert, extra information we can remove. The word cut describes the disk rather than giving that description its own main verb.
- Step 3
Test the semicolons
Could the semicolon version work? A semicolon can join two complete sentences, but One wood sample has no main verb before the first semicolon. The disk description can't stand alone either. The semicolons break apart the sample, its description, and its verb, which need to stay in one sentence.
- Step 4
Match both ends
An insert in the middle needs matching marks at both ends. The version with a comma followed by a dash makes a mixed pair, and the version with a dash followed by a comma does too. The version with paired dashes sets off a thin disk cut from the trunk without breaking the main sentence. Choice B.