"你对这件事情有什么意见？"

Translation: What is your opinion regarding this matter?

[hippietrail]

I got this right but what function does "对" have in the sentence?

[WillowsofXihu]

An English equivalent in this sentence could be "regarding", "on" or "about". See Peace's comment.

[hippietrail]

Thanks. It should also accept "of this matter" at least in this specific sentence.

[KX3.]

And "this issue", for that matter.

[Patrick_Dark]

It means "regarding" yielding a sentence that literally means "You, regarding this matter, have what opinion?"

[PeaceJoyPancakes]

It signifies that the sentiment is directed "towards" the matter in question.

• https://resources.allsetlearning.com/chinese/grammar/Using_%22dui%22_with_verbs#Other_Usage
• https://resources.allsetlearning.com/chinese/grammar/Comparing_%22dui%22_and_%22duiyu%22

[MelvinCheah]

"Do you have any opinions on this issue?"

Would that not work, too?

[PeaceJoyPancakes]

I think it's okay. "Issue" might technically be closer to "问题", but in some contexts "issue" and "matter" are pretty much synonymous.

[KX3.]

Yes, I wanted to put that but changed to matter. Is it marked wrong?

[yuxqii._]

regarding this matter what is your opinion