-- Scott Perl， Albuquerque， NM A: Auto racers have told us the main advantage in filling tires with nitrogen instead of ambient air is that nitrogen tends to maintain more consistent tire pressure over a wide range of As friction between the tire and pavement drives up the temperature， air with varying amounts of moisture content responds differently and can cause inconsistencies in tire While racing drivers are more likely to notice the advantages of nitrogen than everyday drivers， we haven't heard of any disadvantages to using Skeptics question the practice， noting that ambient air is about 80% nitrogen and that it expands and contracts at the same rate as pure A number of readers say there's no appreciable difference in how the tires will react if filled with nitrogen， especially in everyday Q: Is it safe to use cruise control in rain or on wet pavement? -- Scott Brake， Westminster， C A: Car makers often warn that cruise control should be used only in light traffic on open roads and in good There have been reports of accidents involving cruise control when the car lost traction -- or hydroplaned -- in slippery Some car makers warn that the steady throttle of cruise control -- like keeping one's foot on the gas -- could cause the wheels to spin when they hit a wet or icy patch of Car-company representatives say the cruise- control warnings reflect the fact that drivers should be particularly vigilant when conditions are less than ideal， and cruising along on what amounts to partial autopilot tends to lull some drivers into a false sense of Q: If an automobile manual suggests a certain weight oil (such as， 5W-30)， would adding a quart of a different weight oil (say， 10W-40) between complete oil changes damage the car's engine? -- Gil Ehrenkranz， Potomac， M A: Probably But today's engines generally are more precisely engineered than those of 20 or 30 years Many of us at some point have topped off our cars with whatever oil happened to be available without causing damage -- at least not that we know Auto makers， however， say modern engines can be more sensitive to a change in oil weight， and using the wrong oil， even in small amounts， can hurt an engine's performance and even cause Q: What is a sequential manual transmission? How does it differ from an automatic or a standard manual transmission? -- Harry J Jaffe， Germantown， T A: A sequential manual transmission is a gearbox that requires gear changes to be made in order (first to second to third)， instead of having a shift pattern with a lever that allows the driver to skip Motorcycles have used such transmissions for decades and racing cars began using them years ago because they allow quicker Shifting is usually done through levers， buttons or The sequential transmissions advertised today -- mainly in high- performance cars such as Ferraris， Aston Martins and some BMWs -- are technically manual transmissions， except that the clutch and the gear changes are controlled The advantage is that gear changes can be made more quickly and precisely than a human shifting the old-fashioned Traditionalists say the downside is that they simply aren't as much fun to drive and require less driver
Cars in America(美国的汽车)Cars in AmericaCars are an important part of lifein the United S The car made the UnitedStatesanationon Andit helped to make the United States what it is There are three main reasons why the car became so popular in the United S First of all the country is a huge one and Americans like to move around in The cars provide the most comfortable and cheapest form of The second reason that cars are popular is the fact that the United States never really developed an efficient and inexpensive form of public Long-distance trains have never been as common in the United States as they are in other parts of the Nowadays there is a good system of air service provided by But it is too expensive to be used The third reason is the most important one， The American spirit of independence is what really made cars Americans don't like to wait for a bus， or a train or even a They don't like to have to follow an exact And the freedom a car gives them is what Americans want most to The decrease of gas supplies has caused a big problem for A But the answer will not be a bigger system of public The real solution will have to be a new kind of car， one that does not use so much
My View on Developing the Car IndustryWith the development of modern industry，more and more families are able to have their own But，seeing the problems like air pollution and the reduction of resources，some people appeal for the reduction of private Still，I think there is every reason for the even faster development of the car Thanks to the development of the car industry， we do not have to cram in the buses， but can enjoy free travel in own cars， we can go to more places in a leisure Transportation becomes comfortable and But there are those who worry that too many cars may cause more traffic problems， serious:air pollution and the exhaustion ofresources， While these problems may be true， they can be solved and some are being For example， we can invent cars that: can save fuel or use other types of energy so that cars can still ＇be used even though resources run To reduce pollution， people have manufactured many cars without We can relieve the traffic pressure by building more and more roads or-adopt computer-monitored automated For all the contemporary problems cars bring， no one can deny the convenience cars bring us and ignore the effort We make to solve these Therefore，the development of the car industry is necessary， and it should develop as quickly as
