The basic principle of radar is illustrated by what happens when one shouts in a e. The echoof the shouting 11 the walls helps a person determine the size of i cave. With radar, however , the waves are radio waves instead of 12 waves. dio waves travel 13 the speed of light, about 300,000 kilometers in a second. A lar set 14 a short burst of radio waves. Then it receives the echoes 15 when waves bounce (Silt) off objects. By determining the time it 16 for the echoes to imi to the radar set, a trained technician 17 determine the distance between the [ar set and other objects. The word "radar", 18 , gets its name from the term dio detection and ranging." "Ranging" is the term for detection of the 19 between object and the radar set.

A . centrifugal pumps B . jet pumps C . propeller pumps D . reciprocating pum

A . to avoid the rearrangement of the cargo loaded on board B . to ensure the safety of the ship and cargo C . to reject the damaged cargo during loading operation D . to prevent the spontaneous combustion of coal and grai

A . Magnetic materials of the same polarity repel each other and those of opposite polarity attract B . The Earth's magnetic lines of force are parallel to the surface of the Earth C . Magnetic meridians connect points of equal magnetic variation D . The compass needle(s) will，when properly compensated，lie parallel to the isogonic lines of the Earth

A、Consideration B、Clarity C、Control D、Conciseness

A、Separation of Powers. B、Checks and Balances. C、Individual Rights. D、Federalism.

For want of better names， we shall call these two classes immediate reward and delayed reward. In general， the kind of news which may be expected to give immediate reward are news ofcrime and corruption， accidents and disasters， sports， social events， and human interest. Delayedreward may be expected from news of public affairs， economic matters， social problems， science， education， and health. News of the first kind pays its rewards at once. A reader can enjoy an indirect experiencewithout any of the dangers or stresses involved. He can tremble wildly at an axe-murder， shake his head sympathetically and safely at a hurricane， identify himself with the winning team， laughunderstandingly at a warm little story of children or dogs. News of the second kind， however， pays its rewards later. It sometimes requires the reader totolerate unpleasantness or annoyance — as， for example， when he reads of the threatening foreignituation， the mounting national debt， rising taxes， falling market， scarce housing， and cancer. It has a kind of “threat value.” It is read so that the reader may be informed and prepared. When a reader selects delayed reward news， he pulls himself into the world of surrounding reality to which he can adapt himself only by hard work. When he selects news of the other kind， he usually withdraws from the world of threatening reality toward the dream world. For any individual， of course， the boundaries of these two classes are not stable. For example， asociologist may read news of crime as a social problem， rather than for its immediate reward. Acoach may read a sports story for its threat value: he may have to play that team next week. Apolitician may read an account of his latest successful public meeting， not for its delayed reward， but very much as his wife reads an account of a party. In any given story of corruption or disaster， a thoughtful reader may receive not only the immediate reward of indirect experience， but also the delayed reward of information and preparedness. Therefore， while the division of categories holds in general， an individual’s tendency may transfer any story from one kind of reading to another， or divide the experience between the two kinds of reward. What news stories do you read？ Division of news stories People expect to get （71） ▲ from reading news. News stories are roughly divided into two classes. Some news will excite their readers instantly while others won’t. （72） ▲ of the two classes News of immediate reward will seemingly take their readers to the very frightening scene without actual （73） ▲ . Readers will associate themselves closely with what happens in the news stories and （74） ▲ similar feelings with those involved. News of delayed reward will make readers suffer， or present a（75） ▲ to them. News of delayed reward will induce the reader to （76） ▲ for the reality while news of immediate reward will lead the reader to （77） ▲ from the reality. Unstable boundaries of the two classes What readers expect from news stories are largely shaped by their （78） ▲ . Serious readers will both get excited over what happens in some news stories and （79） ▲ themselves to the reality. Thus， the division， on the whole， （80） ▲ on the reader. __________

Macao also benefits from the principles of “one country, two systems”. ()

A． open market rate B．surcharges C． service cost D． stowage factor

A．Bernard Shaw B．Oscar Wilde C．Lawrence D．Hardy