A punctuation question about extra information tests where an added detail begins and ends. Read around the blank, then cross out the detail to check that a complete sentence remains. Commas or dashes can mark both ends of a detail, using the same mark at each end. A semicolon joins complete sentences, while a colon follows a complete sentence and introduces what follows. A pause alone doesn’t tell you which mark belongs in the blank.
Hints
- Hint 1
Read from “Bald eagles” through “have rebounded” and find who the sentence is about and what they’ve done.
- Hint 2
Try removing the words about the eagles’ earlier situation. Then check the punctuation at both ends of that detail.
Step-by-step
Find the insert and match its marks
Step 1Find where the sentence continues
The comma in Bald eagles, once comes before a description of the eagles’ earlier situation. To punctuate this sentence, we need to see where that description ends and the main sentence continues. What have the eagles done? They have rebounded significantly, so the sentence picks up again after the blank.
- Step 2
Test the added detail
Can we remove the description without breaking the sentence? Cross out once on the brink of ____, and we get: Bald eagles have rebounded significantly in the past few decades. That still works as a complete sentence, so the description is an insert, extra information the sentence can do without.
- Step 3
Close the insert
What mark closes an insert opened by the comma after Bald eagles,? A comma must close what a comma opened, since an insert in the middle needs matching marks. Put that closing comma after extinction, and extinction, gives us the pair we need. Choice B.