1.   And today, the vital questions still remain unanswered.

2.   At this point a key question remains unanswered.

3.   But the question of how that electricity was to be distributed remained unanswered.

4.   Many other questions remain unanswered.

5.   Some important questions remain unanswered.

6.   There are still a great many questions that remain unanswered.

7.   Some of the most important questions remain unanswered.

8.   The discussion section should also point out what questions remain unanswered and perhaps suggest directions for further research.

9.   Walking the half-mile to Chapel market, she turned over and over in her mind the many questions about the murder that remained unanswered.

10.   The question of which type of cell is most likely to give the desired result remains unanswered, but work such as theirs will help to elucidate this matter.