练习：
1. What is Alvin?
A A research institute.
B A transporting vehicle.
C A submersible.
D A scientist.
2. Which of the following statements is NOT a fact about Alvin?
A h can carry explorers as deep as 6，500 meters.
B It has played a key role in various important undersea expeditions
C It was launched in the sixties of the twentieth century.
D It has been used for more than 40 years.
3. “...a world that is still full of mysteries” refers to
A the earth.
B out space.
C the ocean.
D Mars.
4. In what aspects are the new HOV and Alvin similar?
A Size.
B Speed.
C Capacity.
D Shape.
5. In what aspects are the new HOV and Alvin different?
A Offering better views.
B Speed.
C Size.
D Both A and B.
答案与题解：
1. C 短文第一段的第四、第五句提供了答案。
2. A 文章第一段从第三句开始说，科学家正在研制一艘可将研究人员带到6 500米深处的潜水装置，而它将替代Alvin，因为Alvin只能潜到4 500米深处。A不是事实，所以是正确选择。
3. C 本文讨论探索海底世界的潜水装置，所以“充满神秘色彩的世界”指的就是海洋。
4. D 第三段的头三个句子告诉我们，HOV和Alvin在体积上和容量上相似。所以D是正确选择。
5. D 第三段最后两句告诉我们，Alvin只有三个窗户，而HOV有五个。最后一段告诉我们，两艘潜水装置的上下活动速度和行进速度有所差别。所以D是正确选择。