Because each family is different, no single system works for everyone.

Of about 25,000 who entered the single system in a given year, half left after a week and did not come back.

A single system for all seemed an obvious solution to such problems.

One key feature of a State is that it should have a single financial system.

All city agencies except the police are on a single e-mail system now, down from six before the Year 2000 program began.

There are 57 nations, each with its own agenda, that have to agree on a single system.

By the 1950s the commission was operating as a single integrated system.

The three libraries were merged into a single system in 1976.

"But homeowners should think of the front door and its frame as a single, integrated system."

The tree has one or more trunks, that all come from a single system of roots.