(A) A survey showed that [over 90 percent of the residents(S) would vote(V) if they(S) had(V) time].
(B) In the not-too-distant future, it seems likely that [the device(S) could be(V) just as common at home as a blackboard(S) is(V) in classrooms].
※比較を簡単にすると、the device(S) is(V) as common(C) <at home> = a blackboard(S) is(V) (common)(C:省略) <in classrooms>
参考にしてください。