Tugs can be used to carry large vehicles.

What was used to carry most mail after the colonies became a nation?

根据材料，完成题。

Air Transportation

1. Airplanes are used to carry passengers， cargo and mail. Air transport companies operate scheduled airlines and non-scheduled services over local， regional， national， and international routes. The aircraft operated by these companies range from small single-engine planes to large multiengine jet transports.

2. The first air passenger services began in 1910， when dirigibles began operation between several German cities. The first scheduled airplane service to carry passengers began in the U. S in 1914. Several experimental airmail flights took place in India， Europe， and the United States before World War I， but air transport service did not become a true business until after the war.

3. During World War Two， intercontinental air transport became firmly established. After the war the new long-distance transports with advanced facilities were increasingly able to avoid storms and strong wind and make flights more economical and consistent. A new generation of "jumbo-jet" transports began operations in 1970， and the supersonic transport entered passenger service in 1976.

4. During the 1970s the number of domestic passengers on U. S airlines increased about 78%， and during the 1980s the figure was up about 58%. In 1990 there were 41.8 million international passengers， the figure was a 75% increase over 1980. The total cargo flown by U. S airlines almost doubled during the 1980s， from 5.7 billion to 10.6 billion ton-miles in 1990.

5. Major airports provide a wide range of facilities for the convenience of millions of travelers. These range from such basic services as ticket-sales counters and restaurants to luxury hotels， shopping centers and play areas for children. International airports must also have customs areas and currency exchange counters and so on.

Paragraph 2__________. 查看材料

A.Airport services

B.Training of pilots

C.Beginning period

D.Rapid growth in the U.S.

E.Development

F.Competition

听力原文：There are two primary ways that genes can be used to treat disease. The first is gene therapy, in which one or more genes are injected into the patient to replace those that are absent or not working properly. This approach has been used to treat heart disease and many forms of cancer. The second way to exploit genes to treat disease is known as small-molecule therapy. In this approach, a small-molecule (that is a drug) is given to the patient to modify the function of one or more genes in the body.

According to the speaker, small-molecule therapy can be used to ______.

A．replace genes not functioning properly in the body

B．increase the number of genes working properly in the body

C．modify the function of some genes in the body

D．replace genes absent in the body

In favor of gender-neutral terms, which of the following words can be used to describe unisex entities? ______

A．Mankind.

B．Chairperson.

C．Superman.

D．Dragon lady.

The credit card makes it unnecessary to carry a large a large amount of cash with you and can be used to_____ an emergency.

A.in place of

B.in case of

C.in favor of

D.in consequence of

How many methods can be used for fixing the shipment date?

Illustrators can be used independently of verbal messages.()

A.Automatic belt

B.Automatic conveyor

C.Automatic Guided Vehicle

D.Robot

Computer games can be used to help children develop their reading skills.（ ）

A．Right

B．Wrong

C．Not mentioned

Computer games can be used to help children develop their reading skills.

A．Right

B．Wrong

C．Not mentioned