Secondly, given that much of this centres on antenatal genetic testing, the notion of holding a doctor responsible for single instances of false negatives violates basic statistical... (newscientist.com)
The chapter on consideration, Chapter 5, offers a literal wilderness of single instances where a statement in one case is contradicted in another. (slaw.ca)
Only single instance (= 1 MP mission) of the game mode is allowed. (makearmanotwar.com)