question problem可数吗

例句：

Lawlessness is a major problem.

违反法律是一个严重的'问题。

The problem is well documented.

这个问题有很多依据。

The problem won't just disappear.

这个问题不会就这样不了了之的。

That's a very hard question.

那是个很难的问题。

He couldn't answer the question.

他没有能回答那个问题。