[see also: problem, issue, matter, subject, topic, point
An obvious question to ask is whether Theorem 1 continues to hold for......
A natural question is how sharp the bounds given in Theorem 6 are.
The question of whether B is ever strictly larger than A remains open. [Or: The question whether]
The question as to how often we should expect the class number to be divisible by p is also of some interest.
The question we shall be concerned with is whether or not f is......
The question naturally arises whether this representation is unique.
The lemma raises an interesting question:......
It is generally a highly nontrivial question whether......
This suggests a question: under what conditions is it true that...... ?
Here the interesting questions are not about individual examples, but about the asymptotic behaviour of the set of examples as one or another of the invariants (such as the genus) goes to infinity.
Put this way, the question is not precise enough.
This question was answered negatively in [5]. However, on the positive side, Davies [5] proved that......
When A is commutative, the answer to both questions is “yes''.
The two questions listed below remain unanswered.
The continuum in question is then called arc-like.