第三节：完形填空（共15小题；每小题1分，满分15分）
阅读下面短文，掌握其大意，然后从51～65题所给的A、B、C和D项中，选出最佳选项，并在答题卡上将该项涂黑。
Strange things happen to time when you travel. __51___the earth is divided into 24 time zones, one hour apart, you can have days with __52___ or fewer than 24 hours, and  weeks with more or fewer than seven days.
If you __53___ a five-day trip across the Atlantic Ocean, your __54___ enters a different time zone every __55___. As you enter each zone, the time __56___ one hour. Traveling west, you set your clock back;  traveling east, you set it __57___. Each day of your trip has __58___ 25 or 23 hours.
If you travel by ship across the Pacific, you ___59___ the international date line. By agreement, this is the point _60___ a new day begins. __61___ you cross the line, you change your __62___ one full day, backward __63____ forward. Traveling east, today __64___ yesterday; traveling west, __65___ is tomorrow!
51.   A. Because      B. If        C. Although     D. When
52.   A. much        B. more     C. many        D. less
53.   A. do          B. make      C. go          D. travel
54.   A. plane        B. train      C. car         D. ship
55.   A. day         B. night      C. hour        D. time
56.   A. goes        B. changes    C. shows       D. adds
57.   A. ahead       B. upward    C. backward     D. fast
58.   A. neither      B. either      C. both        D. nor
59.A. travel       B. trip        C. cover        D. cross
60.A. which      B. what      C. that         D. where
61.A. When      B. Where     C. While       D. Before
62.A. time       B. calendar    C. date        D. hour
63.A. and       B. or         C. but         D. still
64.A. changes     B. makes     C. becomes    D. goes
65.A. which       B. this       C. that        D. it