How to Use "impromptu" with Example Sentences

1. The stunning results of this impromptu survey prompted further investigation .

2. Security forces at a impromptu checkpoint marked by a small minibus wave us by .

3. Later in his impromptu speech mr sha turned to an american colleague , singling out bob orr , from the executive office of the secretary-general .

4. His speech was met with impromptu applause .

5. Would it have been better to hear the impromptu ramblings of a nervous speaker in total cognitive meltdown ?