题目

如图是在高速公路上用超声波测速仪测量车速的示意图，测速仪发出并接收超声波脉冲信号，根据发出和接收到的信号间的时间差，测出被测物体的速度．现测速仪对距其x=380m的匀速行驶中的汽车发出超声波信号，超声波信号从发出到被反射回来的时间间隔△t=2.0s，超声波在空气中传播的速度是 v声=340m/s，则当测速仪接收到被反射回来的超声波信号时，汽车前进的距离为（ ） A . 100m B . 60m C . 80m D . 120m10．Money management （管理） skill is very important for us，but many parents don't take time to teach their children about the value of money，and unfortunately，many of those children grow up to be adults who struggles with money management skill．What age should parents begin educating their children about money？Financial （金融） experts agree that it's never too early．The more children learn about money，the more they will be able to make wise financial decisions as they grow older．First，parents can begin teaching young children how to count money．It is very important for young child．Next，you can teach the value of saving．Once they learn that saving is a good idea and that it is something they should always do，their financial future will be brighter．For example，your child wants a new bicycle．You can teach them to save part of their allowance （零用钱）for that bike，while still keeping money for ice cream，or for going to the movies with their friends．In this way they will begin to understand the value of both short-term saving and long-term saving．It's never too early，also，to teach your child different ways to make money．For example，they can sweep the floor，wash dishes and so on．Sit down with your children and talk with them in some ways they would like to earn money．You'll be surprised and glad at the effort they will begin making．Help your children chart their financial course in life，teach them basic money management skills，and their future will be brighter．41．When should parents teach their children how to master （掌握） some money management skills？CA．As children grow up．B．As children are teenagers．C．As early as possible．D．When they go to school．42．When children are very young，in order to educate them about money，first，parentsmay start withA．A．teaching them to count money B．teaching them to make moneyC．teaching them to save money D．teaching them to go shopping with money43．Which of the following is NOT true according to the underlined sentences？CA．Buying a new bike needs a long-term saving．B．Keeping some money for ice cream shows the value of a short-term saving．C．Keeping some money for going to the movies with friends shows the value oflong-term saving．D．It shows us how we should teach children the value of saving．44．From the passage，we can know thatB．A．money management skills must be taught when children are teenagersB．if we teach children basic money management skills，their future will be brighterC．we shouldn't ask children to learn to make money by themselves before they grow upD．we should tell children how to spend money45．The best title of the passage can beD．A．Parents and Children B．Children Should Learn to Save MoneyC．We Should Save Money D．Teaching Children About Managing Money．