第三部分：阅读理解 (共20小题；每小题2分, 满分40分)
阅读下列短文，从每题所给的四个选项(A、B、C和D)中，选出最佳选项。
When you look at a map of the Caribbean, you will see a bunch of little islands surrounded by. Blue waters, which include places that aren't always household names like Montserrat and Anguilla.
While some of the names may not be familiar, the fact is that the Caribbean is a popular vacation region. Those little clots on the map often turn out to be island paradises. There are more than 7,000 islands, islets, and reefs in the area, many of which are lightly populated and stunningly beautiful.
The biggest challenge you might face in planning your trip is choosing where in the Caribbean to go. All of the nations feature excellent weather. Most feature beautiful beaches. You can enjoy the waters in most of the Caribbean nations and as is often the case with island nations, you will be welcomed warmly by the locals. Here are some resources to help you.
Unless you can walk on water or you cruise the Caribbean, the best way to visit is to fly. Some destinations have more frequent and cheaper flights than others. You should do some comparison shopping on flights to the Caribbean. And if you are planning on flying there during the Christmas holiday weeks it's important to book as early as possible because prices will just keep going up as they get closer.
The Caribbean offers a wide variety of accommodation options. Check out the Caribbean hotels that are available to get a better idea of the various options. If you are on a tight budget then, the Caribbean could be challenging, as there are only a few cheap hotels and hostels that might help you save some money.
Many people see the Caribbean from a cruise ship. There is no shortage of cruises that will take you through the region. Cruise and Vacation Travel Packages is the place to go to find the cruise or vacation package that is right for you.
56. The Caribbean is popular with tourists because ________.
A. the area has a small population B. the area has a long history.
C. there are many beautiful islands there D. tire area is very developed
57. The underlined word "they" in the fourth paragraph refers to _________.
A. prices of air tickets B. tourists to the Caribbean
C. flights to the Caribbean D. the Christmas holiday weeks
58. Which of the following statements is NOT true according to the passage?
A. The weather in all of the Caribbean nations is fine.
B. Most of the Caribbean hotels are cheap.
C. The local people of the Caribbean are very friendly.
D. It is hard to choose a destination in the Caribbean.
O2(g) ＝ H2O(g) ΔH1＝a kJ·mol-1
的最低能量叫键能。从化学键的角度分析，化学反应的过程就是反应物的化学键的破坏和生成物的化学键的形成过程。在化学反应过程中，拆开化学键需要消耗能量，形成化学键又会释放能量。
2NH3(g) △H＝a kJ·mol－1。试根据表中所列键能数据估算a 的值：_______________。
__。