+0
The bunch of flowers (has, have) faded although i put (it, them) in water the moment (it, they) were cut.

We have complained to the Health Department about it but so far (it, they ) (hasn't haven't) done anything about it.

The management (does, do) (its, their) best to help the workers.

In my opinion, i will use plural for number 1, singular for number 2, and singular for number 3. Though understanding that agreement for collective noun as such should be assessed by looking at the context of the subject, i m still confused, especially on how to explain them to my students. Could somebody teach me how to determine the answers for the above questions. Thank you.
+0
I would say 'they" for the Health Department. It's very, very common to refer to unspecified officials as "they."

"They oughta pass a law" "When are 'they' going to do something about that?"
+0
In #1, I would agree with SK (has, them, they); and in #2, with GG (they, haven't).

In #3, I would use the singular if the sentence was a statement by the management, and the plural where e.g. an obsequious employee was talking about the management.

MrP
Site Hint: Check out our list of pronunciation videos.
Comments  
The bunch of flowers (has, have) faded although i put (it, them) in water the moment (it, they) were cut.

We have complained to the Health Department about it but so far (it, they ) (hasn't haven't) done anything about it.

The management (does, do) (its, their) best to help the workers.
SusankayThe bunch of flowers (has, have) faded although i put (it, them) in water the moment (it, they) were cut.

Actually, if we refer to the "bunch of flower" it should use the singular verb (has) and you got it right. But your second part shifted to "them" inferring to the flowers ,which IMO is not correct.

We have complained to the Health Department about it but so far (it, they ) (hasn't haven't) done anything about it.

The management (does, do) (its, their) best to help the workers.
 BarbaraPA's reply was promoted to an answer.
Students: Are you brave enough to let our tutors analyse your pronunciation?
 MrPedantic's reply was promoted to an answer.