a (the) series of + 复数名词，谓语动词常用单数形式。

The series of five games was completed yesterday.

一连串五场的比赛昨天已结束。

A series of lectures is scheduled.    一连串的演讲排定了。

There has been a whole series of accidents on the road recently.

最近在这条路上发生了一连串事故。

但如果对一系列的东西逐一加以考虑时，谓语动词也可用复数形式。

A serious of problems is / are to be discussed at the meeting.

以下是英国BBC节目中的原文：

Series 3 returns to your screens in 2010. This series has now ended, but a new series of Lark Rise to Candleford has been commissioned.

www.bbc.co.uk/larkrise/about/