3 Silicon nitride

A、Alumina (Al2O3)

B、Phosphorus pentoxide (P2O5)

C、Silicon nitride (Si3N4)

D、Aluminum nitride (AlN)

A.

B.

C.

D.

A、A、Ceramics

B、B、Cemented Carbide

C、C 、Poly Crystalline Diamond

D、D、Cubic Boron Nitride

Section B

Directions: In this section, you will hear 3 short passages. At the end of each passage, you will hear some questions. Both the passage and the questions will be spoken only once. After you hear a question, you must choose the best answer from the four choices marked A, B, C and D.

听力原文： The use of silicon is basic to the developments which have taken place since the 1950s. This element has special electrical properties. It is a semiconductor, half way between a full conductor such as copper and an insulator like plastic. By adding small amounts of other chemicals to pieces of silicon and then joining the resulting different types together in various ways, a very fast, efficient "switch" can be produced.

As manufacturing processes grew more and more sophisticated, it became possible to pack more and more individual transistors onto a single piece of silicon called chip. These chips are at most 1 centimeter square and a fraction of a millimeter thick. In 1960 a chip could hold one transistor. Today it can contain as many as a million.

Silicon chips are changing our world at an enormous pace. They affect or will affect all aspects of our lives—industry, transportation, finance, education, medicine, communication, domestic and recreational spheres. By using micro-technology, computers can now be made with an almost infinite operational capacity. The cost is actually decreasing while their speed of operation is increasing. Their micro-components will last indefinitely under normal conditions.

(27)

A．Use of copper conductors.

B．Use of plastic insulator(绝缘体).

C．Use of silicon(硅) semiconductors.

D．Elimination of chemicals.

the third, and most dramatic, such wave【2】by the computer industry in the last twenty-five years. The first wave【3】tangible products—"hardware," as【4】the computer programs that【5】software. In the 1960s and 1970s companies in the Santa Clara Valley, between San Jose and San Francisco, produced silicon memory chips for computers—【6】the name Silicon Valley. Then they produced silicon logic chips,【7】direct a computer's operation. Then many produced computers【8】.

The great【9】from the hardware era include those of the Hewlett and Packard families, of Hewlett-Packard, which started【10】money in the presilicon era, with scientific instruments. The Packard Foundation, with【11】 of ＄10 billion, recently【12】the Ford Foundation as the nation's third-largest private foundation The【13】hardware company of the 1990s is Intel,【14】Pentium and other processing chips are used in most personal computers【15】the Macintosh.

The second【16】of wealth creation involved software—"application" software that people use for work or recreation, like word-processing programs or computer games, and "systems" software used to【17】businesses or, very often, computer networks【18】. The difference between software and hardware provides a classic illustration of【19】economists mean by "increasing returns to scale." Because the cost of producing additional units of software—the "marginal cost"- is extremely low,【20】you become the market leader in a field, your profits grow astronomically.

(1)

A．fortune

B．fortunes

C．property

D．estate

2. Fill in the blanks with the appropriate words（每小题2分，共40分） (1) A 1) is characterized by having a well-structured periodic placement of atoms. The smallest assembly of atoms that can be repeated to form the entire crystal is called a 2) , with a dimension of 3) . (2) For any semiconductor there is a forbidden energy range in which allowed states cannot exist. Energy regions or energy bands are permitted above and below this energy gap. The upper bands are called the 4) ; the lower bands, the 5) . The separation between the energy of the lowest conduction band and that of the highest valence band is called the 6) or energy gap Eg, which is one of the most-important parameters in semiconductor physics. (3) For an n-type silicon, a substitutional phosphorous atom with five valence electrons has replaced a silicon atom and a negative-charged electron is donated to the lattice in the conduction band. The phosphorous atom is called a 7) . When a boron atom with three valence electrons substitutes for a silicon atom, a positive-charged hole is created in the valence band and an additional electron will be accepted to form four covalent bonds around the boron. This is p-type, and the boron is an 8) . We can calculate the approximate distance of the donor electron from the donor impurity ion, and also the approximate energy required to elevate the donor electron into the conduction band. This energy is referred to as the 9) . (4) Electronic devices rely on transport of electrons (holes) in materials. This transport occurs either under the influence of an electric 10) or carrier concentration 11) . There are two collision or scattering mechanisms that dominate in a semiconductor and affect the carrier 12) : phonon or 13) scattering, and 14) scattering. If the carrier energy is large enough it can transfer energy to the lattice by the emission of an optical phonon. This mechanism is very efficient and limits the maximum drift velocity. The limiting value for the drift velocity is termed the 15) . Besides the 16) , which flows when an electric field is applied and which follows Ohm's law, an additional important component of current can flow if a spatial variation of carrier energies or densities exists within the material. This component of current is called 17) . (5) The bipolar transistor has three separately doped regions and two pn 18) . The three terminal connections are called the emitter, base, and 19) . The width of the 20) region is small compared to the minority carrier diffusion length.

选出应填入下面一段英语中______内的正确答案。

Future Computer Trends:

The components of a PC will be built into the(1)and large plasma or electroluminesent flat panel display hanging on a partition wall act as both a(2)and videophone display.

A high resolution, touch sensitive LCD(3)into desktop will allow pen-based pointing and data input. In the home, meanwhile, computers will become as ubiquitous as TVs.

Computer interfaces will be far friendlier than(4)graphical user interfaces (GUI) of today. Computer will use "human interfaces" based on multimedia.

RISC microprocessors will finally obliterate the ever thinning gap between workstations and PCs. Similar advances in nonvolatile flash memory will lead to the replacement of magnetic(5)disks with electronic "silicon disks".

供选择的答案：

(1) build (2) monitor (3) desk (4) built

(5) mouse-drive (6) keyboard (7) touch-sensitive (8) soft

(9) hard (10) optical

A.Silicon

B.Carbon

C.Oxygen

D.Nitrogen