___________ 查看材料

A. education
B. status
C. knowledge
D. location

Thecourse gives you basic instructions in car maintenance.

A. coaching
B. idea
C. term
D. aspect

Some Knowledge in Physics<br>1．The sun is the source of most of heat known to us. As a direct source of heat, the sun maintains life upon this planet, 150,000,000 kilometers distant. It is also an indirect source of heat. Since the earth is derived from the sun, it is to the latter that we must trace some of the earth's internal heat that reveals itself through volcanoes, geysers (喷泉),and hot springs.<br>2．An insect is not afraid of gravity, but it is in deadly fear of another force of nature. This force is called surface tension (张力). A man coming out of a bath carries with him a film of water a bout one fiftieth of an inch in thickness. This weighs about a pound. A wet mouse has to carry its own weight in water. A wet fly has to lift many times its own weight, and, as everyone knows, a fly once wetted by water or any other liquid is in a very serious position indeed. An insect going for a drink is in as great danger as a man leaning over the edge of a cliff in search of food. If it once falls into the grip of the surface tension of the water--that is to say, gets wet--it is likely to remain so until it drowns. A few insects contrive to be unwettable; the majority keep away from their drink by means of long proboscis (喙).<br>3．When the temperature of a liquid is raised enough, the liquid boils. This means that bubbles of vapor, containing millions of molecules form. below the surface. In order for such bubbles to be produced, the pressure of the vapor inside them must be equal to the pressure of the air upon the surface of the liquid. If the air pressure is greater, the bubble will collapse. The boiling point of a liquid, then, is the temperature at which the vapor pressure of the liquid is equal to the atmospheric pressure upon the liquid at the surface.<br>4．Solids also expand with increase in temperature and contract when cooled. But they do not behave quite so uniformly (相同地) in this respect as liquids and gases do, particularly in the case of wide variations, in temperature. Most solids expand or contract by a definite amount for every degree of the temperature that rises or falls. The amount by which no substance expands and contracts for one degree is not usually the same as that for a different substance. Thus, for a given rise in temperature, a piece of brass expands a little more than a piece of copper and much more than a piece of steel of the same size.<br>5．Electric trains have many advantages over those drawn by steam engines. There is no smoke to soil the passengers' clothes and the cushions in the train. Because they carry on heavy loads of coal and water, these trains can start and stop with less waste of power. In a station they are silent: there's no steam to produce noise to deafen the passengers.<br>A Insects and Surface Tension<br>B Expansion and Contraction<br>C Temperature of Boiling Point of Liquids<br>D Principals in physics<br>E Advantages of Electric Trains<br>F The Solar Energy<br>Paragraph 2 ______

The reason for the medical benefits of laughter relates to______

The idea of the national boundaries in often different from______.

Watching Microcurrents Flow<br>We can now watch electricity as it flows through even the tiniest circuits. By scanning the magnetic field generated as electric currents flow through objects, physicists have managed(46). The technology will allow manufacturers to scan microchips for faults, as well as revealing microscopic defects in anything from aircraft to banknotes.<br>Gang Xiao and Ben Schrag at Brown University in Providence, Rhode Island, visualize the current by measuring subtle changes in the magnetic field of an object and(47)<br>Their sensor is adapted from an existing piece of technology that is used to measure large magnetic fields in computer hard drives. "We redesigned the magnetic sensor to make it capable of measuring very weak changes in magnetic fields," says Xiao.<br>The resulting device is capable of detecting a current as weak as 10 microamperes, even when the wire is buried deep within a chip, and it shows up features as small as 40 nanometers across.<br>At present, engineers looking for defects in a chip have to peel off the layers and examine the circuits visually; this is one of the obstacles(48). But the new magnetic microscope is sensitive enough to look inside chips and reveal faults such as short circuits, nicks in the wires or electro migration -- where a dense area of current picks up surrounding atoms and moves them along. "It is like watching a river flow," explains Xiao.<br>As well as scanning tiny circuits, the microscope can be used to reveal the internal structure of any object capable of conducting electricity. For example, it could look directly at microscopic cracks in an aeroplane's fuselage,(49). The technique cannot yet pick up electrical activity in the human brain because the current there is too small, but Xiao doesn't rule it out in the future. "I can never say never," he says.<br>Although the researchers have only just made the technical details of the microscope public, it is already on sale, from electronics company Micro Magnetics in Fall River, Massachusetts. It is currently the size of a refrigerator and takes several minutes to scan a circuit, but Xiao and Schrag are working(50).

A. to shrink it to the size of a desktop computer and cut the scanning time to 30 seconds
B. to making chips any smaller
C. to take tiny chips we require
D. to picture the progress of the currents
E. converting the information into a color picture showing the density of current at each point
F. faults in the metal strip of a forged banknote or bacteria in a water sample

The energy wasted by the electronic devices in the U.S. is sufficient to ______.

When a Chinese and an English-speaking child learn their own language, their biggest difference lies in the fact that______.

Invisibility Ring<br>Scientists can"t yet make an invisibility cloak like the one that Harry Potter uses. But， for the first time， they"ve constructed a simple cloaking device that makes itself and something placed inside it invisible to microwaves.<br>When a person "sees" an object， his or her eye senses many different waves of visible light as they bounce off the object. The eye and brain then work together to organize the sensations and reconstruct the object"s original shape. So， to make an object invisible， scientists have to keep waves from bouncing off it. And they have to make sure the object casts no shadow. Otherwise， the absence of reflected light on one side would give the object away.<br>Invisibility isn"t possible yet with waves of light that the human eye can see. But it is now possible with microwaves. Like visible light， microwaves are a form. of radiant energy. They are part of the electromagnetic spectrum， which also includes radio waves， infrared light， ultravioletmys， X rays， and gamma rays. The wave lengths of microwaves are shorter than those of radio waves but longer than those of visible light.<br>The scientists" new "invisibility device" is the size of a drink coaster and shaped likearing. The ring is made of a special material with unusual ability. When microwaves strike thering， very few bounce off it. Instead， they pass through the ring， which bends the waves all the way around until they reach the opposite side. The waves then return to their original paths.<br>To a detector set up to receive microwaves on the other side of the ring， it looks as if the waves never changed their paths as if there were no object in the way! So， the ring is effectively invisible.<br>When the researchers put a small copper loop inside the ring， it， too， is nearly invisible.<br>However， the cloaking device and anything inside it do cast a pale shadow. And the device works only for microwaves， not for visible light or any kind of electromagnetic radiation. So， Harry Potter"s invisibility cloak doesn"t have any real competition yet.<br>Harry Potter is mentioned in the passage， because scientists __________. 查看材料

A. can now make an invisible cloak of the same kind as he uses
B. try to make an invisible cloak of the same kind as he uses
C. try to invent a device similar in idea to the invisible cloak he uses
D. know that it is possible to make an invisible cloak of the same kind

What Is the Coolest Gas in the Universe？<br>What is the coldest air temperature ever recorded on Earth？ Where was this low temperature recorded？ The coldest recorded temperature on Earth was -90℃, which __________ (51) in Antarctica (南极洲 ) in 1983.<br>We encounter an interesting situation when we discuss temperatures in __________ (52).<br>Temperatures in Earth orbit (轨道) actually range from about + 120℃ to -120℃. The temperature depends upon __________ (53) you are in direct sunlight or in shade. Obviously, -120℃ is colder than our body can __________ (54) endure.<br>The space temperatures just discussed affect only our area of the solar __________ (55).Obviously, it is hotter closer to the Sun and colder as we travel __________ (56) from the Sun.<br>Scientists estimate temperatures at Pluto are about -210℃. How cold is the lowest estimated temperature in the entire universe？ Again, it depends upon your __________ (57). We are taught it is supposedly __________ (58) to have a temperature below absolute zero, which is -273℃, at which atoms do not move. Two scientists, Cornell and Wieman, have successfully __________ (59)down a gas to a temperature barely above absolute zero. They won a Nobel Prize in Physics in 2001 for their work--not a discovery, in this case.<br>Why is the two scientists&39; work so important to science？<br>In the 1920s, Satyendra Nath Bose was studying an interesting __________ (60) about special light particles (微粒) we now call photons (光子). Bose had trouble __________ (61) other scientists to believe his theory, so he contacted Albert Einstein. Einstein&39;s calculations helped him theorize that atoms __________ (62) behave as Bose thought--but only at very cold temperatures.<br>Scientists have also discovered that ultra-cold (超冷) atoms can help them make the world&39;s atomic clocks even __________ (63) accurate. These clocks are so accurate today they would only lose one second __________ (64) six million years! Such accuracy will help us travel in space because distance is velocity (速度) times time (d=υt). With the long distances involved in space__________ (65), we need to know time as accurately as possible to get accurate distance.$amp;_________ 查看材料;$br＞

A. operated
B. occurred
C. opened
D. offered