21.  For more than two decades, Atlanta has been in violation of the U.S. standard for ozone, the main component in smog.

22.  Generally, the main components of a dish are placed neatly in the center of the plate and surrounded by sauce that covers the base of the plate.

23.  From their work, published in Science, the main components of the miniature machine can be recognized, although much remains to be understood about its operation.

24.  Hops, the main component for taste, comes in trucks from Washington and Oregon.

25.  It is the main component of exhaust fumes.

26.  Its main component, Higuchi said, is setting up a system where failing teachers are evaluated and supported by a peer review team.

27.  Net interest income, the main component of operating profit, was down in the period.

28.  NATO, for its part, insists on forming the main component of any peacekeeping force.

29.  Nitrogen has a variety of industrial uses, and is used as main component in fertilizers.

30.  Now, with the passage of its version of the budget bill, the Senate has put the main components of the pending tax legislation into useful focus.