Statements: All roads are streets. Some streets are lanes. No lane is a highway. Conclusions: I. Some streets are not highways.
II. All streets being highways is a possibility. Which conclusion(s) logically follow(s)?

Some streets are lanes and no lane is a highway, so those lane-streets are not highways — 'Some streets are not highways' definitely follows (I). Because at least some streets (the lanes) cannot be highways, it is impossible for ALL streets to be highways — II does not follow.