27.
C. the/the/a/the
("The linguist specialized in the Arabic language. She spent years studying a local dialect in the remote parts of the Middle East.")

28.
A. x/x/the/x
("When I went to Hawaii, my favorite island was Kauai. I spent three days hiking along the Na Pali Coast and three days lying on Poipu Beach.")

29.
A. the/x/the
("Explorers first reached the Moon in 1969.")

30.
B. the/the/the
("While we were in the South Pole in 1911, first climbed the Mt. Everest in 1953, and first set foot on the Moon.")

31.
A. x/the/the/x/x
("While in New York, we walked across the Brooklyn Bridge, went to the top of the Empire State Building, attended a basketball game at the Madison Square Garden, and visited the Museum of Modern Art.")

32.
B. the/the
("Unfortunately, the whole day yesterday I had to spend studying for my biology test, but I won't know the results until next week.")

33.
B. x/the/the
("I really loved the morning and finding all the gifts from Santa under the tree.")

34.
C. a/a/the
("I'm so stressed out at work; I really need to take a whole month off and just relax on a tropical beach somewhere. Maybe I can do that the next summer.")

35.
A. a/the/the
("When I was a kid, I spent the summer on the beach in Florida. Now, I have to work.")

36.
D. x/the
("Do you want to meet for dinner on Wednesday? Or if you prefer, we could get together the next Monday.")

37.
A. an/x
("I was on the phone with them for an entire hour and nobody could answer my question.")

38.
B. the/the/the
("The conference started at noon and didn't finish until late in the evening. We spent the whole time listening to boring speeches.")

39.
A. x/the
("Have you ever heard of Halloween? It's a holiday that Americans celebrate on the 31st of October.")

40.
D. the/the
("I didn't sleep at all the last night. I spent the whole night lying awake.")

41.
C. the/x
("I didn't know that the Great Lakes were so large until we went there last year.")

42.
D. the/the
("We stayed at the Plaza, a world-famous hotel near the Central Park.")

43.
A. the/the/the
("I always enjoy driving over the Golden Gate Bridge. It has a lovely view over the San Francisco and the Pacific.")

44.
B. the/the/the
("While we were in the Georgia, we went canoeing in the Okefenokee Swamp and camped along the Suwannee River.")

45.
B. x/the/the
("On her first day in Paris, Cindy visited the Notre Dame Cathedral and the Eiffel Tower.")

46.
B. the/the/the
("Although she hates museums, on her second day in Paris, Cindy visited the Louvre to see the Mona Lisa, the most famous painting in the world.")

47.
C. x/x/the/the
("Have you ever heard of Malta? It's an island in the Mediterranean.")

48.
A. the/the/x
("When we went hiking in the Alps, we saw many famous mountains including the Matterhorn.")

49.
B. the/x
("When Stan attended the Harvard University, he lived in a small, off-campus apartment.")

50.
C. the/the/the
("Our trip to the Namib Desert, Namibia, was so adventurous! We explored the Fish River Canyon, the Skeleton Coast, and the Etosha National Park.")