Each year in the fall, when the weather starts to cool in the northern hemisphere, millions of North American monarch
butterﬂies journey south. Searching for food and warmer habitats, they ______ thousands of miles—from as far north as
Canada all the way down to Mexico—on this annual migration.
ﬂew
were ﬂying
had ﬂown
ﬂy
Choice D is the best answer. The convention being tested is the use of verbs to express tense. In this choice, the present
tense verb “ﬂy” is consistent with the other present tense verb ( “journey”) used to describe the butterﬂies’ yearly migration.
Together, these simple present tense verbs correctly indicate that the migration is a current, yearly occurrence.
Choice A is incorrect. The simple past tense verb “ﬂew” isn’t consistent with the other present tense verb used to describe
the butterﬂies’ yearly migration. Choice B is incorrect. The past progressive tense verb “were ﬂying” isn’t consistent with the
other present tense verb used to describe the butterﬂies’ yearly migration. Choice C is incorrect. The past perfect tense verb
“had ﬂown” isn’t consistent with the other present tense verb used to describe the butterﬂies’ yearly migration.