There is no single answer to the question.

这个问题的答案不是唯一的。

He is by far the best. There is no question about it (= it is completely certain).

他显然是最好的。这毫无疑问。

He was questioned by the police.

他受到警方的审问。

No one questioned his ideas for almost 2,000 years.

将近2000年，没有人怀疑过他的看法。

Soon you will also question whether the voice you're hearing is actually real.

不久你也会怀疑你听到的声音是否不是真人。