Early in the 18th century a French doctor used steel springs to hold teeth in place. However, it was difficult to close one’s mouth! Late in the same century porcelain (瓷)teeth set in gold were often used to make false teeth.

Although the use of artificial teeth increased, human teeth continued to be used also. In the 19th century, teeth from soldiers killed in battle were made into artificial teeth. For example, teeth from the dead in the American Civil War were sent to England.

By the middle of the 19th century, an American doctor, Claudius Ash, invented a better kind of porcelain tooth made of a special kind of hard rubber.

26.When did people with the earliest false teeth live according to the passage?
[A] At the end of the 17th century.
[B] In the early 18th century.
[C] In the middle of the 19th century.
[D] Over 2,500 years ago.
27.Which material would wealthy people use to make artificial teeth in 1693?
[A] Porcelain. [B] Hard rubber.
[C] Ivory. [D] Bone.
28.Who first used steel springs to tie false teeth together according to the passage?
[A] An Italian doctor. [B] A French doctor.
[C] An American doctor. [D] An English doctor.
29.We can learn from the passage that ___________.
[A] one looked older than his real age with artificial teeth
[B] we are using the same method as ancient people in making false teeth
[C] poor people would often sell their teeth to get money in the 17th century
[D] human teeth were no longer used in making false teeth after the 18th century
30.The passage is mainly about ___________.
[A] the discovery of false teeth [B] the material of false teeth
[C] the use of false teeth [D] the history of false teeth

Passage Three

Questions 31 to 35 are based on the following passage.

Trademarks (商标) identify and distinguish the products of one business firm from those of another. It may include a word, a sentence, a name, a symbol, a picture, or any combination of these. Trademarks must be attached directly to the product. Many trademarks contain the name of the owner of the business. But manufacturers often use some word to describe the qualities of the product, or make up a word. The spoken part of a trademark is called the brand name.

Trademarks provide a simple way for people to determine who is responsible for a particular item. They also help people identify the brands they liked in the past so they may purchase them again. Manufacturers use trademarks to promote the sale of their goods.

Service marks also identify goods and services. They do not have to be attached to a product. Companies that provide services to the public, such as transportation companies, use these marks to advertise their services. For example, a blue sign with a bell, the symbol of the American Telephone and Telegraph Company, tells every passer-by that a public telephone is available for use.

Laws to protect the rights of the trademark owner were developed in the early 1800’s.Most countries now provide for regulation and registration of trademarks. An important protection for trademark rights is federal　(联邦的)registration. In 1905, the U.S. Congress passed the first federal law on trademark registration to be held constitutional.