The principal financial problem faced by older people is poverty.

You told me that the principal problem was to break him out of his apathy.

The principal problem with wine by the glass is price.

A principal problem for the law is to keep various kinds of experimentation within bounds.

A principal problem that universities face is students' laxity toward security.

Housing, health care and unemployment are Indians' principal problems here, she said.

The principal problem about them has generally been said to be that of their meaning or semantics.

Private war was one of the principal problems faced by the central government, far more so than in relatively centralized England.

These were considered the nation's principal economic problems, and are all components of "stagflation."

His principal problem, he says, is that his feet hurt.