先找出规律,再填入合适的数.(1)39511121814(2)132079178 发布时间:2017-04-12 10:53 │ 来源:www.tikuol.com 题型:解答题 问题: 先找出规律,再填入合适的数.(1)39511121814(2)13207917859
题型:解答题 一警车上的警报器发射频率f="1" 000 Hz的声波,警车远离静止的观察者向一悬崖行驶,车速v="10" m/s,已知声音在空气中的传播速度为v声="330" m/s,试问:(1)观察者直接从警报器听到的声音频率是多大?(2)观察者听到从悬崖反射的声音频率是多大? 查看答案
题型:解答题 With good reasons he is called a fool.A.With good reasons is he called a fool.B.He is called fool with a good reason.C.With good reasons he is called fool.D.He is called fool with good reasons. 查看答案