It fails to prevent pregnancy at least 10 percent of the time.

"But we failed to prevent the terrorist act," he said.

He also failed to prevent a massacre of all the French in the city.

But in general these steps fail to prevent many small farms from going under.

The decision, which was largely expected, failed to prevent another increase in oil prices.

Another question is to what degree the report will single out individuals as failing to prevent the disaster.

Some say they are angry with themselves for failing to prevent their infection.

A central purpose of the federal investigations, he said, has been to protect officials who failed to prevent so much death.

Has the international community failed to prevent the outbreak of violence?

This approach did not in itself cause the wars of 1956 and 1967, but it clearly failed to prevent them.