According to the principle of two stroke diesel engine, what is the number of its efficient work stroke per revolution?（）

A . reciprocating pumps B . positive displacement pumps C . centrifugal pumps D . centripetal pum

A . Gross tonnage B . Net tonnage C . Displacement tonnage D . Deadweight tonnage

A . tightly B . closely C . securely D . strictly

A . which； bring about B . in which； bring up C . on which； bring u

A . filtering B . centrifuging C . depositing D . operating

A . reciprocating pumps B . positive displacement pumps C . centrifugal pumps D . centripetal pum

A . 1/2 B . 1 C . 2 D . 3

A . equipment's B . tools C . apparatus D . aid

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. __________

A、正确 B、错误

A．正确 B．错误

A.adjacentcondition B.parameters C.casecondition D.caserequirement

A．Always referring to RAM． B．Always following the opinion of the majority． C．Always striving for an optimal outcome at the cost of least damag E． D．Always referring to the plan rehearsed beforehanD．

A．families． B．stateswithintheUnitedStates． C．nations． D．Alloftheabovearecorrect．