Question 53·Medium·Form, Structure, and Sense
Over the last decade, comprehensive surveys of urban bird populations, along with satellite imaging, ______ that green roofs play a significant role in supporting migratory species.
Which choice completes the text so that it conforms to the conventions of Standard English?
For subject–verb agreement and tense questions, first strip the sentence down to its core by crossing out modifiers and side phrases like "along with," "as well as," or long prepositional phrases. Identify the true subject and decide whether it is singular or plural. Then, use any time expressions (like "over the last decade," "since 2010," or "currently") to pick the correct tense. Finally, scan the answer choices and eliminate any that are the wrong number (singular/plural) or the wrong tense, leaving the one that matches both the subject and the time clue.
Hints
Locate the true subject
Ignore the descriptive phrases like "of urban bird populations" and "along with satellite imaging." What is the main noun that is doing the action?
Check singular vs. plural
Once you find the main subject, ask: is it singular or plural? Your verb form must match that number.
Use the time phrase as a clue
Look at the phrase "Over the last decade." Which verb tense is usually used for actions that started in the past and continue up to now?
Eliminate by agreement and tense
Cross out any choices that are the wrong number (singular vs. plural) or the wrong tense for the time period described.
Step-by-step Explanation
Find the main subject of the sentence
Identify what is actually doing the action of the verb.
In the phrase "comprehensive surveys of urban bird populations, along with satellite imaging," the core noun is surveys. The words "of urban bird populations" and "along with satellite imaging" are extra information describing the surveys; they are not part of the grammatical subject.
Decide if the subject is singular or plural
The noun surveys is plural. Even though "satellite imaging" (singular) is mentioned, it is introduced by "along with," which works like a side note, not like "and" joining two subjects.
So the subject is plural, and the verb must also be plural.
Match the tense to the time phrase
The sentence starts with "Over the last decade," which describes an action that began in the past and continues up to now.
English typically uses the present perfect tense ("have/has" + past participle) for this kind of time period. So we need a verb that is both:
- plural (to match "surveys"), and
- in the present perfect tense (to match "over the last decade").
Choose the option that fits both number and tense
Now check each answer choice:
- "demonstrates" and "demonstrate" are simple present, not present perfect.
- "has demonstrated" is present perfect but singular, which does not match the plural subject.
- Only one option is present perfect and plural, so that is the correct choice: "have demonstrated."