翻译：As the source of aluminum is almost inexhaustible, we can expect that more and more uses will be found for this versatile metal. （Passage Two）

to separate from the ores(矿石) in which it was found that its price was higher than that of gold. The price remained high until a new process was discovered for refining the metal with the aid of electricity approximately three quarters of a century later. The new method was so much cheaper that aluminum became practical for many purposes, one of which was making pots and pans.

Aluminum is lightweight, rustproof and easily shaped into different forms. By mixing it with other metals, scientist have been able to produce a variety of alloys, some of which have the strength of steel but weigh only one third as much.

Today, the uses of aluminum are innumerable. Perhaps its most important use is in transportation. Aluminum is found in the engines of automobiles, in the hulls of boats. It is also used in many parts of airplanes. In fact, the huge "airbus" planes would probably never have been produced if aluminum did not exist. By making vehicles lighter in weight aluminum has greatly reduced the amount of fuel needed to move them. Aluminum is also being used extensively in the building industry in some countries.

Since aluminum is such a versatile(多用的) metal, it is fortunate that bauxite(铝土矿) , which is one of its chief sources, is also one of the earth's most plentiful substances. As the source of aluminum is almost inexhaustible, we can expect that more and more uses will be found for this versatile metal.

The price of aluminum was sharply reduced when people discovered a new refining process with the aid of______.

A．wind power

B．solar energy

C．hydraulic power

D．electricity

minerals and vast quantities of the rocks that contain them. The best aluminum ore is bauxite, defined as aggregates of aluminous minerals, more or less impure, in which aluminum is present as hydrated oxides. Bauxite is the richest of all those aluminous rocks that occur in large quantities, and it yields alumina, the intermediate product required for the production of aluminum. Alumina also occurs naturally as the mineral corundum, but corundum is not found in large deposits of high purity, and therefore it is an impractical source for making aluminum. Most of the many abundant nonbauxite aluminous minerals are silicates, and like all silicate minerals, they are refractory, resistant to analysis, and extremely difficult to process. The aluminum silicates are therefore generally unsuitable alternatives to bauxite because considerably more energy is required to extract alumina from them.

The intermediate product needed for the production of aluminum is______.

A．hydrated oxides

B．bauxite

C．alumina

D．silicates

It is believed that a new technique to ______will probably be found.

A．recycle old aluminum products

B．discover more bauxite ores

C．make aluminum by putting ore particles under water

D．take out aluminum magnetically from poorer ores

Ring groove inserts are occasionally used on aluminum alloy piston to_______.

A.reduce the ring groove wear rate

B.seal against crankcase vapors

C.lessen the wear on aluminum part of the cylinder

D.allow for the greater expansion rate of aluminum

A、paraphrase is almost as long as the original source with different words.

B、A summary should be as short as a sentence.

C、Paraphrase and summary are commonly used in scientific texts.

D、A quotation is an exact copy of the original source.

Aluminum is found on earth mostly in the form. of______.

A．pure metal

B．bauxite

C．gold

D．liquid

It is believed that a new technique to ______ will probably be found.

A．recycle old aluminum products

B．discover more bauxite ores

C．make aluminum by putting ore particles under water

D．take out aluminum magnetically from poorer ores

It is believed that a new technique to ______ will probably be found.

A．recycle old aluminum products

B．discover more bauxite ores

C．make aluminum by putting ore particles under water

D．take out aluminum magnetically from poorer ores