11.   He underwent several hours of surgery.

12.   Maier was flown from the ski resort of Radstadt to a hospital in Salzburg, where he underwent several hours of surgery.

13.   She was expected to undergo several hours of questioning about her views on farm policy, the Forest Service, food safety and other issues.

14.   The Boston University hockey player who was paralyzed after crashing headfirst into the boards remained in guarded condition after undergoing several hours of surgery.

15.   The others underwent several hours of questioning.