Statements: Some threads are needles.
Some needles are strings.
Conclusions: I. Some needles are not strings.
II. Some threads may be strings.
Some needles are strings (I) ⇒ I.I. ⇒ No conclusion. Hence, conclusion I does not follow. Some threads are needles(I) + Some needles are strings(I) ⇒ Probable conclusion ⇒ Some threads may be strings(I). Hence, conclusion II follows.