一件非常引人深思的事。

A very sobering thought.

这是一个引人深思的想法，可是有事实支撑吗？

This is a provocative idea. But do the facts support it?

戴维斯先生给出了一份及时且引人深思的某次搜索的记述：经过50年的搜寻，尚未发生任何目击。

Mr Davies provides a timely and thought-provoking account of a search that, after five decades, has not yet produced any sightings.