In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.

[Q]: Communion is that which is shared between the _ persons of the Holy Trinity.
[A]: three


[Q]: Architectural shingles are twice or _ times as thick as ordinary shingles.
[A]: three


[Q]: Bivalves have _ shell halves that completely enclose the animal.
[A]:
two