1 - Geologists argued that a dramatic drop in sea level coincided with the extinction of the dinosaurs and could have caused the climatic changes that resulted in this extinction as well as the extinction of many ocean species.

2 - The British Medical Association is coming under pressure to support compulsory childhood vaccinations, after a false scare about autism led to a drop in vaccinations and a big jump in measles cases.

3 - If this is the standard to which I have to drop to gain membership, then count me out!

4 - The use of artery-opening stents has helped lead to a sharp drop in the number of patients having cardiac bypass surgery.

5 - A United Nations program called the Global Polio Eradication Initiative is responsible for the drop in world polio cases.