托福听力稿中不懂的地方求帮分析

Question

一个conversation，一个女生的物理课被取消了，但是她不知道，正在咨询处咨询。
1.But if we don't have enough students sign up for the course, the college can't offer it.

是不是有一点语法错误？不应该是:"enough students who signed up for the course"吗？这样的定语从句，引导词是不可省略的啊，它这样说，难道不会产生"have sb. do"结构的歧义吗？

2.-Do you know how many people have to be enrolled in order to keep a class from being cancelled?

-Usually it'd be at least ten people, but since it was cancelled this semester, they might even do it with less.

最后半句不太明白。是他们甚至还会调低报名人数的下线，还是他们他们会更少地这样去做，因为已经取消一次了。请帮忙分析一下，谢谢。

Answer 1

1.语法我也说不清楚，但这句话应该没有问题。这是听力不是改错，大概意思明白就行。
2.意思是平常最少要10个人才能课，但因问上个学去这门课被取消了，有可能少于10个人他们也开课。They might even do it with less如果展开是They might even [keep a class from being cancelled] with less [people].（逻辑想一下，因为上学期像上的人就没上成，所以这学期开课的几率会大一些。）