▲series 虽为复数形式，但可以表示单数意义，即单数与复数同形。series用作主语时，谓语通常用单数，但在现代英语中有时也用复数。如：

The lecture series falls [fall] naturally into three parts. 该系列讲座可自然分成3部分。

▲a series of 用作主语时，谓语也可以用单数或复数。如：

——用单数的例子

A series of robberies has shaken up residents of the neighborhood. 接连发生的抢劫案使这一地区的居民深感不安。

A series of bribery scandals has cut a swathe through the government. 一连串的受贿丑闻使政府遭到重创。

A new series of wildlife programmes has started on Monday evenings. 一档新的野生动物节目已经在每周一晚上播出。

——用复数的例子

A whole series of problems have arisen one after another. 一系列的问题接连出现了。

A series of attacks have sharpened fears of more violence. 一连串的袭击事件增加了人们对发生更多暴力事件的担心。

A series of missed opportunities have badly weakened the company. 一系列的机会错失大大削弱了该公司的实力。

——用单数或复数均可的例子

A series of attacks has [have] sharpened fears of more violence. 一系列的攻击使人们更加担心会有更多的暴力。

I have to attend a series of meetings which has [have] nothing to do with my work. 我不得不要参加一系列与我的工作无关的会议。

▲如果其前有明显的表示复数意义的修饰语，则其后要用复数谓语，比较：

A series of lectures is scheduled. 一个系列演讲已安排好了。

Two series of lectures are scheduled. 两个系列演讲已安排好了。

This new series is beginning next week. 这个新连续剧下周开始播映。

These new series are beginning next week. 这些新连续剧下周开始播映。

——摘自webster老师的解答：

https://www.cpsenglish.com/question/7140