21.   Darwin could have used these seasons in Hollywood as a testing ground.

22.   Education reform will be a first testing ground.

23.   Europe has long been a testing ground for senior investment bankers.

24.   Even with empty seats at concerts, jazz in New York is simultaneously a draw for tourists and a testing ground for musicians and ideas.

25.   Exxon also has scads of filling stations here and often uses Houston as a testing ground for some of its retail innovations.

26.   For Gomperts, Ireland made a sensible testing ground for her pilot project.

27.   For some, the disaster was a professional testing ground.

28.   For nearly a century, the U.S. military has used the jungle terrain surrounding the Panama Canal as a testing ground for explosives and chemical weapons.

29.   For purposes of comparison, I offered only one side of my face as a testing ground.

30.   Gemini was the testing ground for our technology, the training we needed so Apollo could follow and get us to the moon and back.