31.  He said that the transit police were working closely with the New York City police and the Federal Bureau of Investigation to prevent such an attack.

32.  He said his company had built defensive measures into its products that would make them invulnerable to such an attack.

33.  If children worry that they might be involved in such an attack, parents need to be reassuring.

34.  If such an attack were to happen in Bosnia, it could jeopardize the whole U.S. operation.

35.  If the attacker in Kfar Hess was a Palestinian, it would mark the third such shooting attack within Israel in as many Sundays.

36.  If the attacker was a Palestinian, it would mark the third such shooting attack within Israel in as many Sundays.

37.  In Israel, the issue is more complicated because the loyalties of the bombers, the first Israeli Arabs to attempt such an attack, are still unclear.

38.  In congressional testimony, counterterrorism experts say such an attack is all but inevitable.

39.  In that instance, however, concern about a possible popular backlash to a strike on other Muslims led most Arab leaders to publicly warn against such an attack.

40.  In the first such attack in November, a helicopter-fired rocket killed Palestinian gunman Hussein Abayat in Bethlehem.