Choose the words or expressions to complete the passage(选择最恰当的单词或词语，完成短文)
For many years the United States and the other countries used gold and silver as money. Paper money was used to stand for the holdings(储备)of both gold and silver. The value of silver was limited to that of gold. Fifteen ounces(盎司) of silver had the same value of one ounce of gold. These values did not change until after 1860 when mines(银矿)in the west of the United States began to  1 large amounts of silver. This extra amount of silver caused the price of silver to 2    . Then fifteen ounces of silver would no longer buy one ounce of gold. In 1871 Germany declared(宣布)that it would not support its paper money with silver any more. Instead, it would use only gold. Other countries of Europe quickly  3 the same. The United States passed a law in 1973 that prevented the government from using silver as money. Western silver producers protested(抗议)loudly and put much pressure on the  4 makers. Five years later a new law was 5 . It said that the government must buy four and half million ounces of silver each month. The new law increased the amount of silver money. The country had two kinds of quite different views on the issue(发行)silver money. Businessmen, bankers and other rich men wanted to 6  the use of silver money because it made the dollar less valuable. But farmers, laborers and the others who owned the money not only wanted silver money but also wanted an unlimited supply of it.

Many companies use guards and expensive alarm systems to protect their property(财产)。 Soon a new kind of protection will be used- robots. Engineers have been working on the first mobile robots for businesses. The robots will patrol(巡逻) factories, warehoues(仓库)，and museums at night.

The mobile robots will move around slowly on wheels. They will be able to detect people through walls and pick up sounds, such as breaking glass. They can be fixed with lound sirens(警笛) to frighten thieves, or radios to signal police or guards.

To protect a building, a robot will have to move around without knocking into the walls. Information about the building will have to be stored in the robot’s small, built-in computer. A floor map could be programmed into the computer’s memory, for example.

A mobile robot will not be able to do everything. Unlike human guards, it will not be able to climb stairs, open doors, or move along rough ground. It won’t be able to tell the difference between friends and enemies. Because of that, people will have to be barred from the area it patrols.

One kind of mobile robot will be able to “sense” whether a chair or box has been moved and go around it. This robot will also judge size well enough so that it won’t send an alam if a cat crosses the room. And if someone tries to steal this robot, it will sound a loud, painful siren. The three-foot-tall robot will be hard to steal anyway. It will weigh about 200 pounds.

U.S companies pay almost $10 billion a year to protect their property with alarm systems and human guards. Mobile robots may be cheaper.

1.Why is the new kind of robots called mobile robots?

A. Because they are able to climb stairs.   B. Because they are able to send an alarm

C. Because they can open doors.      D. Because they can move around slowly on wheels

2. How will a robot get directions for moving around a building?

A. From a human guard   .        B. From a built- in computer.

C. From another robot   .        D. From radio signals.

3. What does the underlined word barred mean?

A. protected    B.allowed .   C.marked     D. prevented

4. According to the text, a mobile robot will NOT be able to ___________.

A. sense whether something has been moved.   B. sense a cat crossing the room.

C. move over rough ground .                D. detect people through walls.

5.This text mainly describes how robots will ___________.

A. protect the museum                       B. set off a siren .

C. judge the size of a person.         D. patrol buildings.

Many companies use guards and expensive alarm systems to protect their property(财产)。 Soon a new kind of protection will be used- robots. Engineers have been working on the first mobile robots for businesses. The robots will patrol(巡逻) factories, warehoues(仓库)，and museums at night.
The mobile robots will move around slowly on wheels. They will be able to detect people through walls and pick up sounds, such as breaking glass. They can be fixed with lound sirens(警笛) to frighten thieves, or radios to signal police or guards.
To protect a building, a robot will have to move around without knocking into the walls. Information about the building will have to be stored in the robot’s small, built-in computer. A floor map could be programmed into the computer’s memory, for example.
A mobile robot will not be able to do everything. Unlike human guards, it will not be able to climb stairs, open doors, or move along rough ground. It won’t be able to tell the difference between friends and enemies. Because of that, people will have to be barred from the area it patrols.
One kind of mobile robot will be able to “sense” whether a chair or box has been moved and go around it. This robot will also judge size well enough so that it won’t send an alam if a cat crosses the room. And if someone tries to steal this robot, it will sound a loud, painful siren. The three-foot-tall robot will be hard to steal anyway. It will weigh about 200 pounds.
U.S companies pay almost $10 billion a year to protect their property with alarm systems and human guards. Mobile robots may be cheaper.
【小题1】Why is the new kind of robots called mobile robots?

1Choose the words or expressions to complete the passage(选择最恰当的单词或词语，完成短文)

For many years the United States and the other countries used gold and silver as money. Paper money was used to stand for the holdings(储备)of both gold and silver. The value of silver was limited to that of gold. Fifteen ounces(盎司) of silver had the same value of one ounce of gold. These values did not change until after 1860 when mines(银矿)in the west of the United States began to  1  large amounts of silver. This extra amount of silver caused the price of silver to 2    . Then fifteen ounces of silver would no longer buy one ounce of gold. In 1871 Germany declared(宣布)that it would not support its paper money with silver any more. Instead, it would use only gold. Other countries of Europe quickly  3  the same. The United States passed a law in 1973 that prevented the government from using silver as money. Western silver producers protested(抗议)loudly and put much pressure on the  4  makers. Five years later a new law was  5  . It said that the government must buy four and half million ounces of silver each month. The new law increased the amount of silver money. The country had two kinds of quite different views on the issue(发行)silver money. Businessmen, bankers and other rich men wanted to  6  the use of silver money because it made the dollar less valuable. But farmers, laborers and the others who owned the money not only wanted silver money but also wanted an unlimited supply of it.

1.A. produce     B. find          C. search        D. dig

2.A. rise        B. lift          C. fall          D. set

3.A. did         B. took          C. made          D. acted.

4.A. law         B. money         C. gold          D. silver

5.A. refused     B. accepted      C. planned       D. passed

6.A. end         B.  continue     C. protect       D. allow