A verb form question tests whether the blank needs a main verb or a describing form. Find the blank's subject and read to the period, setting aside any opening time phrases. A main verb says what the subject does or is, either alone or with a helping verb; -ing, to, and having forms can't do that on their own. Count the main verbs in the blank's part of the sentence. If that part has none, the blank must add one.
Hints
- Hint 1
Look at the two people named in the sentence. Which verb belongs to Brahe, and where does the part about Struve begin?
- Hint 2
Set aside the opening time phrase and read from “Friedrich Struve” to the period. Which words, if any, say what Struve does?
- Hint 3
What does “to identify potential double star systems” tell you about Struve's use of the records? Use that answer to check whether his part has a main verb yet.
Step-by-step
Find Struve's own main verb
Step 1Separate Brahe's event from Struve's
The words after astronomer Tycho Brahe meticulously cataloged the night sky give an earlier event in the opening time phrase, so let's separate it from the sentence about Struve. Who did the cataloging? Brahe did, which means cataloged belongs to the part starting with after. Set the time phrase aside and find Friedrich Struve, the subject, or person the main sentence is about. We need Struve's main verb, the verb that says what he does or is.
- Step 2
Check the words after the blank
Read all the way to the period: to identify potential double star systems tells why Struve used the records. Can to identify be the main verb for Struve? A to form can't be a main verb on its own; here it gives his purpose, as in in order to identify the systems. With the time phrase removed, no word outside the blank says what Struve does. So the blank must give Struve his main verb, not a form that only describes.
- Step 3
Choose the form that can be a main verb
In Friedrich Struve ______ Brahe's records, to consult, consulting, and having consulted can't be the main verb because to, -ing, and having forms can't do that job on their own. Which form can say what Struve does? Would consult can, because would is a helping verb that makes the phrase a main verb for Struve. Although both events are in the past, would can describe a past event that came later than an earlier one. Choice C.