A verb tense question tests whether you can tell when something happens. Check that each choice agrees with the subject, then look for time clues across both sentences. Ask what time the blank’s verb covers, not what date appears nearest. Use the present for current facts or habits, the past for a finished past time, has or have plus a past participle (a form like finished) for a period from the past up to now, and will plus a verb for the future.
Hints
- Hint 1
Look at the start of the second sentence. Find the words that say when the crews’ work happens.
- Hint 2
Use the first sentence to identify what then refers to. Does the second sentence’s time phrase stop at that past moment or extend up to the present?
Step-by-step
Follow the time clue
Step 1Check what the choices change
The subject is construction crews, which means more than one crew. Do the choices differ in whether they fit that subject? They all work with a plural subject, so agreement can’t decide this question. What changes is when the crews do the work.
- Step 2
Trace the time span
What does Since then mean here? In 2020 tells us when the council approved the plan, so then points back to 2020. Since turns that year into a starting point: the sentence reports how much work the crews have done from 2020 up to now. The time span reaches the present, even though it starts in the past.
- Step 3
Choose the form for that span
The present perfect uses has or have with a verb form like completed to report what’s happened from a past starting point up to now. Which helping verb fits construction crews? Because the subject is plural, we use have, giving have completed. Choice C.