China is developing a “supersonic” submarine that could travel from Shanghai to San Francisco in less than two hours.

Researchers say their new craft uses a completely new technique to create a “bubble” to surround itself, cutting down drag dramatically. In theory, the researchers say, a supercavitating（超空泡） ship could reach the speed of sound underwater, or about 5,800km/h. 

The technology was developed by a team of scientists at Harbin Institute of Technology's Complex Flow and Heat Transfer Lab. Li Fengchen, professor of fluid machinery and engineering, told the South China Morning Post he was “very excited by its potential”. 

The new sub is based on Soviet technology developed during the cold war.

Called supercavitation, it envelopes an underwater craft inside an air bubble to avoid problems caused by water drag. A Soviet supercavitation torpedo（鱼雷）called Shakval was able to reach a speed of 370km/h or more - much faster than any other conventional torpedoes. In theory, a supercavitating vessel could reach the speed of sound underwater, or about 5,800km/h, which would reduce the journey time for a transatlantic underwater cruise to less than an hour, and for a transpacific journey to about 100 minutes, according to a report by California Institute of Technology in 2001.

The Chinese system constantly “showers” a special liquid membrane（液态膜）on its own surface. Although this membrane would be worn off by water, in the meantime it could significantly reduce the water drag on the vessel at low speed. After its speed had reached 75km/h or more the vessel would enter the supercavitation state, Li said.  

However, Li admitted problems still needed to be solved before supersonic submarine travel became workable. A powerful underwater rocket engine still needs to be developed. The technique could even be used to aid a swimmer, he believes. “If a swimsuit can create and hold many tiny bubbles in water, it can significantly reduce the water drag; swimming in water could be as effortless as flying in the sky,” he said. 

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1.How does the new craft reduce water drag?

A By reaching the speed of sound.

B By surrounding itself with “bubbles”.

C By running underwater.

D By holding many tiny bubbles in water.

解析：选B。B。细节理解题。根据文章第二段…to create a “bubble” to surround itself, cutting down drag dramatically可知，新式潜艇利用了空泡技术，在外围形成空泡，大大减少了水的阻力。

2.What can be inferred from the passage?

A This “supersonic” submarine is completely made in China.

B This underwater craft travels much faster than sound.

C There is great future for the supersonic submarine.

D The “supersonic” submarine was made in the cold war.

解析：选C。C。推理判断题。根据文章第三段…he was “very excited by its potential”可以判断，新式潜艇具有很大的发展潜力，未来发展前景广阔。

3.What does the underlined word“supercavitation” mean?

A The submarine is like an envelope with bubbles surrounding it.

B The submarine is surrounded by an envelope when traveling underwater.

C Water drag is removed with the supercavitation technology.

D Covering the underwater craft with bubbles to overcome water drag.

解析：选D。D。细节理解题。根据文章第五段it envelopes an underwater craft inside an air bubble to avoid problems caused by water drag可知，所谓超空泡效应，指的是将潜艇包围在空泡之内，从而达到减少水阻力的目的。

4.What does a swimmer benefit from the technique?

A He can swim in water very fast with little effort.

B He can wear a swimsuit that can reduce water drag.

C He can swim very fast with water bubbles surrounding him.

D He can reach the speed of sound when he swims.

解析：选A。A。细节理解题。根据文章第七段If a swimsuit can create and hold many tiny bubbles in water, … swimming in water could be as effortless as flying in the sky可知，超空泡技术应用于泳装之后，可以使游泳运动员不用费力就能很容易提高速度。

5.What can be the best title of the passage?

A The Technology of Supercavitation.

B China’s New Submarine Travels at Sound Speed.

C Swimsuit Benefits from Submarine Technique.

D More Work Needed to Perfect China’s New Submarine.

解析：选B。B。主旨大意题。通读全文可知，本文介绍了中国潜艇应用超空泡技术提高巡航速度的情况。故选B。

6.How many nicknames does New Orleans have?

A Three nicknames.

B Five nicknames.

C More than ten nicknames.

D 　More than twenty nicknames.

解析：选D。细节理解题。 从第一段的第三行 “One web site lists its more than twenty nicknames.”可知，一个网站列举它的二十多个昵称，故选D。

7.Which is NOT New Orleans’s nickname?

A Sin City.

B The Big Easy.

C The Birthplace of Jazz.

D NOLA.

解析：选A。整体理解题。文章第一段提到的昵称是“The Big Easy”，最后一段提到的昵称是 “The Birthplace of Jazz”和“NOLA”，因此没有 “Sin City”。故选A。

8.When did they make the book “The Big Easy” into a film?

A In the early 1700s.

B In 1970.

C In 1987.

D In the 1970s.

解析：选C。细节理解题。从第二段的倒数第二句 “In 1987, they made that book into a film.”可知，是在1987年把这本书制作成了电影。 故选C。

9.New Orleans _______.

A has the most nicknames in America

B has the same pace of life as New York

C is the most famous city in America

D is the biggest city in America

解析：选A。整体理解题。从第一段的”New Orleans probably has more nicknames than any other American city.”可知，新奥尔良比其他城市的昵称都多，因此A正确。而从第二段的第五句”She compared the easy-going way of life there to the hurried pace (步调) of life in New York City.”可知，B不正确；C.最出名的城市；D.最大的城市，文中都没提到。故选A。

10.Which sentence is wrong about “The Big Easy”?

A It shows the slow and easy-going way of life in New Orleans.

B It was a dance hall in New Orleans in the early 1900s.

C It was a newspaper writer’s name in 1970s.

D It was the name of one of James Conaway’s books.

解析：选C。整体理解题。从第一段最后一句可知A正确；从第二段的第二句可知B正确；从第二段的倒数第四句In 1970, James Conaway wrote a book called “The Big Easy”.可知D正确；从第二段的第四句 “That was when a newspaper writer began calling New Orleans by this name.”可知不是这个作者的名字。故选C。