11.   Cantley says he and his teachers are always on the lookout for behavioral changes in students, a sudden drop in grades, hints of trouble at home.

12.   Dissolved carbon dioxide makes air more acidic, so a sudden drop in pH means carbon-dioxide levels are spiking.

13.   Ever heard about the inflatable bra that exploded on an airplane because of a sudden drop in cabin air pressure?

14.   Health officials warned of the effects of such a sudden drop in temperatures and asked people to take special precautions to guard against the frigid winds.

15.   In front, Schmid darted with impressive timing into a fast solo, packed with sign language and sudden twisting drops to the floor.

16.   In any case, the water company quickly detected the sudden drop in pressure and had a crew on the site within a half-hour.

17.   In rare cases, a peanut allergy can cause a sudden drop in blood pressure and the closing of the breathing passages.

18.   Like the airline business, the hotel industry was already hit hard from the sudden drop in corporate travel that hit unexpectedly late last winter.

19.   On Friday, Leon Panetta, the White House chief of staff, asserted that stormy weather was not the only factor behind the sudden drop.

20.   On Wednesday, as those financial problems worsened, a sudden drop in hydroelectric generation pushed the system over it.