Hi there, I'm new here and did not want to post this question in the Grammar area just because I'm a teacher and not a student, sorry if I put it in a wrong place.
I am preparing a class for tomorrow and my teacher's book gives a very weird answer key, here's a part of the text:
"They spent the whole dinner talking about the most unexpected and fascinating things. One could not really tell what they were talking about. Subjects would change in a strange flow of energy - in a secret way one (can - ought to - should) say - constantly spinning over all subjects, diving into one, drowning into one another."
Answer key says *should* but I really can't understand why. My first choice would have been *would* or *might/could* but since they're not available I would select *can* even though it sounds a bit weird but I really can't see *should* in there. Can someone explain it to me? And also then explain why *should* is good but not *ought to*?
Thanks in advance.
PS: I'm teaching this class in less than 12 hours, I just got the book yesterday (late class preparation) but anyway point is I need an answer pretty fast. :) Thank you!