"The principal problem is our schools.
"Imagine if you diagnose a sick person, and you don't mention the principal problem.
The principal problem is those working parents simply do not earn enough to escape poverty.
The principal problem with Scarlett's home-made gown is its weight.
The principal problem with such studies, Mr. Lindert writes, is that they are simulations of a highly simplified world.
The principal problem is that almost all oceanic crust older than about 200 million years has been obliterated by subduction.
Although easing the $5 billion "circular debt" is the principal problem, experts say money is only part of the solution.
But it did virtually nothing to address the principal problem with American elections — which is that the states, not the federal government, run the shows.
The principal problem is that it doesn't have the bandwidth to process a lot of current high-quality downlink material from surveillance aircraft.
Other people seem to be the principal problem; Saturn in opposition signals a phase when colleagues become non-compliant, exes turn truculent and friendships are tested.
Hence, it is just as likely that wage stagnation, not declining birth rates or longer life expectancy, has been the principal problem facing Social Security.
