An agreement question tests whether a verb matches its subject despite other nouns in between. Sort the verb forms by whether they go with it or they, and check whether the blank needs a main verb. An -ing form needs a helper to serve as a main verb. Then find the true subject by asking who or what does what the verb says. Match the subject: one thing needs a singular verb, and more than one needs a plural verb.
Hints
- Hint 1
Look at the verbs in the second sentence. Does the verb after that belong to the whole sentence or to a part with its own subject?
- Hint 2
Cross out the describing phrase before the blank. Would you replace the subject that's left with it or they?
Step-by-step
Find the true subject and match it
Step 1Sort the forms and check the blank
Sort the forms first: shows and has shown go with it, so they're singular, while showing needs a helper to be a main verb. Does the second sentence already have a main verb, the verb saying what its subject does or is? taken at several points along the pipe only describes the measurements, and the verb in the part beginning with that says what the water does. The blank needs a main verb for the measurements.
- Step 2
Find the subject past the description
What gives us the evidence about the water's speed? Cross out taken at several points along the pipe so we can bring the true subject, Measurements, next to the blank. That subject names more than one measurement, so we need a plural verb.
- Step 3
Check the match with they
Replace Measurements with they to test which verb goes with it. We say they show, so the plural form show matches the subject. Choice D.