1.   Keep your pack clean by brushing off any loose dirt after use.

2.   And they say diesel buses can be made just as clean by using upgraded engines, new pollution control devices and low-sulfur fuel.

3.   A broom that will sweep clean by next July because there is not much worth saving here anymore.

4.   I have to keep the tank clean by keeping up the flow of air.

5.   Investigators carefully carried the bag to a specially enclosed room and emptied the letters into a closed biological safety cabinet kept clean by air flows and special seals.

6.   Keep the barbecue grill clean by spraying it with oven cleaner.

7.   Like the hit on Willis, this one was clean by hockey standards and unpenalized.

8.   These pool inhabitants keep the water clean by eating algae and decaying leaves.

9.   His tenure was known for the brutality with which club-wielding workers ensured streets were kept clean by bludgeoning market women selling on the sidewalks.

10.   One woman naively tried to keep clean by crawling on her hands and feet until the net inevitably slammed her to the mud with a stomach churning splat.