题目

I was told that there were about 50 foreign students           Chinese in the school, most           were from Germany. A.study; of whom                                             B.study; of them C.studying; of them                                            D.studying; of  whom 答案：D一辆汽车行驶时的耗油量为0.1升/千米，如图是油箱剩余油量（升）关于加满油后已行驶的路程（千米）的函数图象.（1）根据图象，直接写出汽车行驶400千米时，油箱内的剩余油量，并计算加满油时油箱的油量；（2）求关于的函数关系式，并计算该汽车在剩余油量5升时，已行驶的路程.