A verb form question with a long clause tests whether the blank supplies a main verb or only describes a noun. Sort the forms by their jobs: a main verb says what a subject does or is, while an -ing form needs a helper to do that. Then find the blank's own subject and read to the period, counting only verbs that belong to that subject. A clause needs its own main verb, but adding another without a joining word breaks the sentence.
Hints
- Hint 1
Start at whose and find the blank's own subject. A verb elsewhere in the sentence may belong to a different subject.
- Hint 2
Read past the entire list that follows the blank. What verb comes after that list, and which subject does it belong to?
Step-by-step
Count the study's main verbs
Step 1Find the blank's own clause
The blank follows whose recent study, which opens a clause, a group of words with its own subject and verb. Which subject's verbs should we count? The blank belongs to the study, not to Nair, whose main verb, argues, says what she does. The choices offer main-verb forms and an -ing form without a helper. That -ing form can't be a main verb, so let's follow the study's clause to its end.
- Step 2
Read past the list
Read past the three things named after the blank: isotope analyses, port tax records, and an analysis of gaps in the evidence. What verb comes after that whole list? offers a more cautious account of trade tells us what the study does, so offers is already the study's main verb. The and in port tax records, and an explicit analysis joins things the study includes, not verbs. In earlier models do, do belongs to the models, so it doesn't count as a verb for the study.
- Step 3
Use a form that describes the study
Can the blank add another main verb for the study? Has incorporated, incorporates, and is incorporating would each create a second main verb without a joining word to connect it to offers a more cautious account of trade. The study does the including, so an -ing form can describe what the study includes. Incorporating gives us that form without adding another main verb. Choice A.