这是不是一个"虚拟语气"的用法啊?

问题描述:

这是不是一个"虚拟语气"的用法啊?
我最近在看新概念英语三,看到最近几课觉得有些句子有点奇怪.
所以来问一下,看过的朋友也可以翻书本,我就随便举个例子,Lesson 22.
为了让大家可以联系上下文,把下面一段都发上来.
Some plays are so successful that they run for years on end,In many ways,this is unfortunate for the poor actors who are required to go on repeating the same lines night after night.{==One would expect them to know their parts by heart and never have cause to falter==}.Yet this is not always the case.
括号括起来的就是我想问的句子,是的话最好可以做一下解释?

不是虚拟语气.这里的would可以表示意愿或过去的习惯,理解为“人们总是指望演员们把台词烂熟于心,不出半点差错”.