题目

一段导体两端的电压是24V时，通过的电流是0.5A，则这段导体通电10s产生的热量是__________J；当通过该导体的电流为2A时，其电阻为Ω．           答案：：120      48   解析:：一段导体两端的电压是24V时，通过的电流是0.5A，则这段导体通电10s产生的热量是w=UIt=24v*0.5A*10S=120J, 当通过该导体的电流为2A时，其电阻为R=U/I=24V/0.5A=48欧 China's long-awaited rules on school bus safety finally came into force on Tuesday, including a list of ways aimed at reducing the risk of accident.Among the biggest changes is that buses carrying students will be given priority(优先权) in traffic, while companies and drivers will need licenses to offer school transport services.Officials have spent more than four months making the rules, during which time the country has been shocked by several big crashes because of overcrowded school buses.The latest accident happened on Monday in Yangchun, Guangdong province, in which three kindergarten pupils were killed and 14 others injured.Rules and fundingIn the new rules, a school bus is considered as a vehicle with more than seven seats that is transporting children receiving the State's nine-year compulsory education (ages 6 to 15) to or from school. This can also be for preschoolers(学龄前儿童) if a parent is unable to take them to or from kindergarten（幼儿园）.School buses must also operate in routes marked in the map by governments to ensure safety.PunishmentCompanies and bus drivers who fail to meet the rules face the punishment.Drivers against the rules will be fined 200 yuan ($32) and vehicles will be taken away from its owner if they have been used as an unlicensed school bus.小题1:New safety rules for school buses can ________.A．make the students have a school busB．make fewer accidentC．make the school bus biggerD．punish the parents小题2:The accident happened usually because ________.A．there were more students than there should be in the busB．the road is not wide enoughC．there were not any rule at firstD．companies and drivers faced no punishment小题3:Which of the following is Not true?A．When a truck and a school bus meet, the school bus can go first.B．The students (ages 3—5) mustn’t take school bus according to the rules.C．Those who break the rules will be fined two hundred yuan.D．The school bus has at least 7 seats.小题4:The passage mainly talks about ________.A．the accident in GuangdongB．the school bus safety rulesC．how to punish the driversD．what a school bus is like小题5:A school bus must go _______.A．different ways every dayB．after other busesC．with all the studentsD．the same way all the days