An agreement question tests whether a verb matches its subject, even when a long phrase comes first. Sort the forms by number: one thing takes the verb used with it, and more than one takes the verb used with they. Then ask what the verb is about, checking both sides of the blank. The subject can follow its verb, so put it first to check the match. A nearby noun inside a describing phrase doesn't decide the verb's number.
Hints
- Hint 1
In the second sentence, check both sides of the blank. What does the phrase beginning with from tell you, and what comes after the blank?
- Hint 2
Flip the sentence into its usual order by moving the noun group after the blank to the start. Then ask which noun is being described by of correlations.
Step-by-step
Find the subject after the verb
Step 1Sort by number
Start by sorting the verb forms at the blank in angles _____ a pattern of correlations. The forms emerge, have emerged, and are emerging go with they; the helpers have and are show that those forms are plural. Their tenses differ, but number is the first test: we need to find whether the true subject is one thing or more than one.
- Step 2
Read the opening phrase
Can the nouns before the blank tell us the subject? The phrase beginning with from thousands of trials tells where something comes from, not what that thing is. The words conducted with detectors set at carefully varied angles describe how the trials were run, so detectors and angles stay inside that phrase too. There's no subject before the blank outside that phrase, so this sentence puts its subject after the verb.
- Step 3
Put the subject first
What comes from those trials? a pattern of correlations does, so let's put that group first: a pattern of correlations _____ from thousands of trials. The phrase of correlations tells what kind of pattern appears; it doesn't make correlations the subject. The subject is pattern, which names one thing even though it contains many correlations.
- Step 4
Test with it
Now replace a pattern with it and test the forms in the sentence we've turned around. The check is it emerges, so emerges is the verb form that matches this subject. Choice A.