A verb form question tests whether the blank needs a main verb that says what its subject does or is. Find the subject, who or what the sentence is about, as you sort main verbs from describing forms. Read to the period to see how each verb connects to the sentence. Count main verbs outside extra information and check the blank's own subject. Two main verbs sharing a subject need a joining word; forms linked by and must play the same grammatical role.
Hints
- Hint 1
Find the sentence's subject. Start with "catalog of early field recordings," and ask which noun the rest of the sentence is about.
- Hint 2
Look for a verb that belongs to the sentence's subject near the end. Which verbs belong instead to parts beginning with which or that?
- Hint 3
Check what and connects. How does the phrase after "and thereby" connect to the blank?
Step-by-step
Sort, count, and test
Step 1Find the subject and sort
The catalog of early field recordings is our subject, so we're checking whether it needs a main verb. Sort the forms: has revealed and reveals can be main verbs, revealed needs a test, and an -ing form can't be one alone. Which part can we set aside? The many of which had previously been attributed only to unnamed singers part describes the recordings, so its verb doesn't belong to the catalog.
- Step 2
Read to the main verb
Read past the blank to the words near the period. What has transformed research? The catalog has, so it already has its main verb. In that older inventories overlooked, overlooked belongs to the inventories, not to the catalog. The blank still has the catalog as its subject, and no word joins it to has transformed, so has revealed and reveals would each add a second main verb without a joining word.
- Step 3
Test the past form
Can revealed be a describing form here? Try the was test, adding was before it: the catalog was revealed regional variations doesn't make sense. The catalog shows the regional variations in tempo and ornamentation, so revealed is a main verb here and would add a second one.
- Step 4
Match the linked forms
The words and thereby giving link the blank to giving, which describes what the catalog does. The blank needs a describing form too, so revealing pairs with giving and describes the catalog as it shows regional variations, without adding a main verb. Choice D.