An agreement question tests whether a verb matches its subject when other nouns appear nearby. Read around the blank for a main verb, which says what the subject does or is, then sort the singular and plural forms. Ask who or what the verb belongs to, and set aside phrases that only describe it. One thing takes a singular verb, and more than one takes a plural verb. If the verb contains several words, its helper shows the number.
Hints
- Hint 1
Look at the words immediately after the blank. Does the sentence already have a complete main verb?
- Hint 2
Cross out the words between the commas, then strip the subject down to its main word. Does that word name one thing or more than one?
Step-by-step
Find the subject and complete the verb
Step 1Find the missing helper
The words been carefully restored say what happened to the photographs, but they don't make a complete main verb on their own. What does the blank need to add? It needs a helper that completes the main verb, so having can't work: an -ing form can't be a main verb without its own helper.
- Step 2
Find the true subject
Which word names what's restored? Cross out along with the accompanying captions, which tells us more about the subject rather than adding another subject. Then cross out of the photographs on display, which tells us what group we're talking about. That leaves Each, meaning each one taken alone, so the subject is singular.
- Step 3
Match the helper and its form
Each can be replaced with it, so let's test the helpers with that subject. Have goes with they, while is been restored isn't a valid verb form: is would go directly with restored. The singular helper has also works before been carefully restored, giving it has been carefully restored. Choice B.