21.  It seemed a useful thing to do.

22.  Not so in Massachusetts, which has dismayed the State Department, a useful thing to do.

23.  Proteins are long chains of amino acids that fold up and make interesting shapes that do useful things.

24.  So far, Blair has managed both to do useful things and to refrain from doing too many foolish ones.

25.  Still, some educators think this is useful thing.

26.  The manual tells you useful things, like to unload the gun before cleaning.

27.  The tax code, since its inception, has been used to encourage private Americans to do socially useful things with their money.

28.  The trouble is that not only Diana but the entire royal family has run out of useful things to do.

29.  Useful things, like how to drop in on refreshments-provided staff meetings before the cold cuts are gone, but after the worst of the blather.

30.  We pondered why humans lacked useful things like tails.