题目

一辆汽车的质量为m，额定功率为P，运动中阻力大小为车重的k倍。汽车在水平路面上从静止开始受恒定的牵引力F启动，已知重力加速度为g。则根据上述信息不能求出的是 A．汽车达到额定功率所经历的时间     B．汽车在匀加速过程中牵引力做的功 C．汽车从开始到达到最大速度的过程中所受的阻力做的功  D．汽车运动的最大速度Aggressive pedestrians are in fact as dangerous as careless drivers. They cause traffic accidents, injury and death.These dangerous walkers can be seen in any big city all over the world. About 69% of last year’s pedestrian deaths in the US occurred in urban areas. They cross streets ignoring “DON’T WALK” signals, suddenly appear without warning from behind parked vehicles, walk slowly at crossroads with cell phones attached to heads, blocking traffic.These pedestrians and drivers share a common disregard for the rules of the road, both for selfish reasons. The drivers believe in the power of their machines. If their machines can go faster, they believe they have the right to go faster. If their machines are bigger, they believe they have the right to push smaller vehicles aside. Aggressive pedestrians, on the other hand, believe in the primacy(首位) of the individual, the idea that they are first in any environment, under any circumstances, even when they are on foot in a roaring tide of steel and rubber.Last year, an estimated 5,220 pedestrians died in traffic accidents. Some 69,000 pedestrians were injured. On average, that worked out to one pedestrian killed in a traffic crash every 101 minutes, and one injured every eight minutes. The good news is that the accident rate is dropping. For example, the number of pedestrians killed last year was 24 percent less than the number killed in traffic accidents a decade earlier. The bad news is that the basic causes of pedestrian deaths remain pretty much the same----disregard for traffic signals, inattention and crossing roads under the influence of alcohol and drugs. Alcohol, in fact, was involved in 46 percent of the traffic accidents that resulted in pedestrian deaths. Of those, 31 percent of the pedestrians were found to be drunk.The bottom line is that the pedestrians must do more to protect their lives as well as the lives of other road users. They can start by obeying traffic signals, using marked cross-walks and calling a cab when they’ve had too much to drink.【小题1】The passage is mainly about _____.A．how aggressive pedestrians cause traffic accidentsB．why so many Americans were killed on roads last yearC．what the traffic rules of the road about pedestrians were D．who are to blame for pedestrian deaths, drunk drivers or the aggressive pedestrians【小题2】What is the pedestrians’ selfish reason for traffic jams?A．They know all drivers are skilled and with great care.B．They believe individuals are always first.C．They think traffic rules have nothing to do with them.D．They guess all vehicles will slow down at crossroads.【小题3】 What was NOT the basic cause of pedestrian deaths in the US a decade ago?A．Disregard for traffic signalsB．Paying no attention to surroundings.C．Crossing roads drunk.D．Overspeeding driving.【小题4】What word can best describe the author’s attitude to the traffic accidents caused by pedestrians?A．Excited.B．Cold.C．ConcernedD．Unconnected.