一场问答环节在主新闻发布会之前举行。

A question-and-answer session ___preceded the main press conference.

重要的决定之前应当进行充分的讨论。

Important decisions should be ___preceded by thorough discussion.

这一重大突破之前是数十年默默无闻、细致入微的研究。

This major breakthrough was ___preceded by decades of quiet, meticulous research.