How do you ask someone their opinion in Japanese?
「What is your opinion of ○」は日本語で何と言いますか？

Question

Answer

（here you must put the subject of which you want to receive the opinion of someone else.）+ についてどう思いますか。

例えば

日本語の勉強についてどう思いますか
What do you think about the study of the Japanese language?

Answer

○についてどう思われますか。
○についていかがお考えですか。

Both of the above sentences are polite way to say that.