1.   After only two airings, the series has proved itself full of thorny moral challenges that make points about medicine and ethics.

2.   But expanding to a factory posed some thorny challenges.

3.   But gaining control of One Penn Plaza presents a thorny challenge for Roth, whose company is one of the most voracious buyers of real estate in New York.

4.   Drugs like Clozaril, says Duckworth, present thorny psychological challenges for many patients.

5.   Goldberg acknowledged that he faced a thorny challenge.

6.   So the drug traffickers are faced with the thorny challenge of physically repatriating their profits.

7.   Though any merger often involves thorny challenges in getting former competitors to cooperate, Breuer said Deutsche planned to move swiftly to integrate the operations of both banks.

8.   But entertainment companies face thorny new challenges from the Internet and digital technologies, which make it easy to reproduce movies flawlessly and distribute them illegally in an instant.