Statements: Some years are months
All months are weeks.
All weeks are days
Conclusions: I. All days are months.
II. Some months may not be years.
III. No week may be days.
Some years are months (I) ⇒ conversion ⇒ Some months are years (I) ⇒ probable conclusion ⇒ Some months may not be years.(O). Hence, II follows.