1.   What puzzles most researchers is just why the area in southwestern Colorado was abruptly abandoned by its ancient citizenry.

2.   Although their presence puzzles researchers, the appearance of these great cetaceans dazzles boaters.

3.   Initially, the researchers were puzzled by their findings.

4.   Researchers are also puzzled by differences among the different forms of the disease in various species.

5.   Tests on samples from a Hong Kong toddler who died of viral pneumonia puzzled researchers there.

6.   This explains the coordinated movements of elephants, which had puzzled researchers for years.