21.   The navy has dismissed allegations that the missiles could blast off by themselves, saying the lack of electric power on board excludes even a theoretical possibility of that.

22.   The theoretical possibility has prompted the FDA to re-examine the blood safety question frequently.

23.   The theoretical possibility, however, has prompted the FDA to re-examine blood safety frequently and revise restrictions on donors as needed.

24.   The theoretical possibility, however, has prompted the FDA to re-examine the blood safety question frequently.