1.   Have emission checked at least once a year.

2.   The new program will put vehicles on a treadmill-like device to check their emissions during acceleration.

3.   Airplanes are used to check gas emissions.

4.   Emissions are rarely checked and few vehicles are equipped with pollution-control devices.

5.   Most of the problems occurred with dynamometers, the equipment that simulates driving conditions to check auto emissions.

6.   Most of the problems occurred with dynamometers, the new equipment that simulates driving conditions to check auto emissions.