1.   Because the whitebark pine is not commercially valuable, the U.S. Forest Service is not spending money for research or solutions to the rust problem.

2.   The cars later suffered from serious rust problems and aluminum engine blocks that frequently had to be replaced.

3.   He said rust problems reported in the past had all but vanished.

4.   Stuart-Watt denied that the bridge had a serious rust problem, had worn through and was dangerous in key structural areas.