11.   All the airports are big economic engines for the Valley of the Sun, as the Phoenixarea is known.

12.   But as the state economists and policy-makers look to biotech as its next economic engine, they are counting on Harvard to work alongside industry as never before.

13.   But as an economic engine, biotech is awfully slow to rev up and never likely to provide the horsepower of traditional manufacturing.

14.   But as intellectual property has developed into a primary economic engine, US employers are no longer restricting these agreements to the top tier of the corporate hierarchy.

15.   But few can deny that millions of Mexican migrants, legal and illegal, have been a spark plug in the U.S. economic engine.

16.   But economic distress remains widespread compared with that of the rest of the nation, and more economic engines like Pikeville are needed in the region, Kiernan said.

17.   But the Clinton administration wasted the opportunity to invest in housing, transportation and public space, or to revitalize the urban core as an economic engine.

18.   But the Fed cannot act solely as an economic engine.

19.   But there are newly encouraging signs that those economic engines can drive future growth when the economy rebounds, according to a major report released this week.

20.   But there are newly encouraging signs that those economic engines can drive future growth when the economy rebounds, according to a major report released Monday.