Cfrtjryk

In a blog, we have "Topics"

In stackoverflow, we have "Questions"

What single term do we use if we want to ask for opinions?
(I find the sentence "ask for opinions" to be too long, and I must find single word to replace it, just like Questions & Topics)

How about poll?

5 a : a questioning or canvassing of persons selected at random or by quota to obtain information or opinions to be analyzed

(source: Merriam-Webster)

consult is the verb routinely used for seeking an opinion.

So (in the British parliament) a government is required to “consult” bodies and persons that might be affected by proposed legislation.

In medicine, if a doctor suspects an illness in which s/he is not expert, s/he ‘consults’ a specialist (who have the professional title ‘consultants’). ‘Management consultants’ are people from whom businesses and business people seek opinions/advice. They consult them. We speak of ancient Greeks ‘consulting’ the oracle at Delphi.

So I suggest ‘consult.

If you're after what people think about a film or a show they have seen, or about a product they have bought, "critical review" is current usage.

"Opinions" and "suggestions" are simpler terms and may fit, depending on context.

In newspapers they have a 'vox pop' where they ask people their opinions on issues of the day. It derives from the Latin vox populi (‘the people's voice’). It's a pretty common term here in Australia?

For your title define the act of asking for an opinion, consider propose:

Put forward (an idea or plan) for consideration or discussion by others.
‘he proposed a new nine-point peace plan’
_{Oxford Living Dictionaries}

Use Proposals for a term analogous to Questions:

A plan or suggestion, especially a formal or written one, put forward for consideration by others.
‘a set of proposals for a major new high-speed rail link’
_{Oxford Living Dictionaries}