An agreement question tests whether a verb matches its subject, who or what the sentence is about. First, sort the forms by whether they go with it or they. One thing takes a singular verb; more than one takes a plural verb. An -ing form needs a helping verb. Then check whether the sentence still needs a main verb, which says what the subject does or is. To find the true subject, cross out describing phrases so nearby nouns don't steer your choice.
Hints
- Hint 1
Read through the period. Does the verb after that belong to the same part of the sentence as the blank?
- Hint 2
Look at the phrase beginning with of. What does it describe, and what would be left if you crossed it out?
- Hint 3
Replace the true subject with it or they. Does the subject name one group or more than one group?
Step-by-step
Sort forms, then find the true subject
Step 1Sort the verb forms
The choices give different verb forms for a panel of leading climate scientists ______, so let's check which subjects they match and whether they can be main verbs. A main verb says what the subject does or is. For a subject such as it, a regular present-tense verb ends in -s; for a subject such as they, it uses the base form. The -ing form needs a helper to be a main verb.
- Step 2
Find the missing verb's subject
Does the verb in has increased significantly over the past decade already do the blank's job? No, because it belongs to the clause beginning with that, a group of words with its own subject and verb. That means asserting would leave the sentence without a main verb, so which subject must the missing verb match? In a panel of leading climate scientists, cross out of leading climate scientists, which tells us who is on the panel. The true subject is the panel, not the scientists inside that phrase.
- Step 3
Match one group to its verb
Is a panel one thing or more than one? A panel names one group, even though it has many members, so its verb is singular. That rules out assert and have asserted, which need a plural subject. The singular form is asserts: it asserts gives the singular form the sentence needs. Choice B.