11.   Although a year has passed since word of the selection, critical questions remain unanswered.

12.   And one leading expert said the mouse experiments did not address the critical question of how the medicine might work in someone already exhibiting the characteristic smallpox lesions.

13.   Another critical question this summer will concern the Olympics.

14.   As the debate begins, the conflict between Talbott and Mandelbaum promises to provide a fascinating subplot, as well as a guide to the critical questions about expansion.

15.   Behind the failure and recriminations lies one critical unanswered question.

16.   Besides the black turnout, a critical question for both candidates is how big the new-voter turnout will be and which way it will go.

17.   A critical question in the wake of the impeachment struggle is whether Clinton and Congress can overcome the anger and partisan bitterness and work together.

18.   A critical question left unanswered by the new lawsuit is how and why the scheme was not uncovered by the auditors.

19.   A critical question in off-year elections is voter turnout.

20.   A critical question is whether senior conservatives with credibility in their party will step forward to lead negotiations.