记者在新闻发布会上提出了一系列问题。

The reporter fired off ___a ___string ___of questions during the press conference.

作为一名作家，她取得了一系列成功。

As a writer, she's enjoyed ___a ___string ___of successes.

城市已经发展，随着增长带来了一系列多年前未曾想到的问题。

Cities have grown, bringing with this growth ___a ___string ___of problems which were not thought of years ago.