series是单复数一体的词,所以谓语动词时复数。series n.（单复同）系列,连续,丛书

例：

1)five series of products

2)silver white series

例句：

She produced a TV series about adopted children.

她拍了一部描写收养儿童的电视系列片。

Users advance through the program by answering a series of questions.

用户通过回答一系列问题，逐步完成整个程序。

The training programme takes the form of a series of workshops.

培训课程采取一系列研讨会的形式。