I do not know which one or ones should work best.

The better ones work so often that they don't have to leave town to get by.

Far as he knows, you and me are the only ones working this new case.

But the ones that were already there would still work.

The short ones worked, but the long ball broke up.

"We are giving people the tools and the chance to find out which ones work for them."

The old system had been removed, but the new ones were not yet working at full power.

Add or change medicines if the current ones are not working.

The ones who were young and very poor worked just as hard, albeit at a different kind of work.

"So how do you choose which ones to work on?"