21.  Burnett is a tough one.

22.  But after his first visit to Kosovo, he was convinced that the job ahead for CARE and other humanitarian organizations there is going to be a tough one.

23.  But for South Korea the line between humanitarian concerns and political realities is a tough one to draw.

24.  But for South Korea the line between humanitarian concerns and political realities is a particularly tough one to draw.

25.  But it was a tough one.

26.  But remember the computer marketplace is a tough one.

27.  But the audience turned out to be a tough one.

28.  But the decision to allow fast-food chains to open within hospitals can be a tough one.

29.  But the last couple of years, even with winning the Super Bowls, have been tough ones physically.

30.  But the last few years had been tough ones.