上期IV版:
Day 1 1-4 ABDB Day 2 1-4 CDCD
Day 3 1-4 CADB Day 4 1-4 ABDC
Day 5 1-5 BCDAF
本期II版:
III. The writer’s dad liked four-way stops because he saw them as proof that humans could behave rationally for everyone’s benefit.