1.   Authoritative warnings have been sounded, such as that of George F. Kennan in The New York Times.

2.   A few early warnings had been sounded.

3.   A similar warning was sounded last week by former European Commission President Jacques Delors.

4.   Again, warnings were sounded.

5.   But a warning had been sounded.

6.   For several years, the warnings have been sounded with increasing urgency, but not much response.

7.   It is not sufficient to simply go to the basement when warnings are sounded.

8.   The one-year warning has been sounded.

9.   When a warning was sounded, the nurse examined the patient and worked with a psychiatrist to plan treatment.

10.   Initial investigations showed that both engines and crew were operating normally and no cockpit warnings were sounded until shortly after the plane left the ground.