题目

下列说法正确的是（    ）A.若发生多普勒效应，则波源的频率改变B.若你以声波的速度随同某一个波峰一起远离声源，你将听不到声音C.你听到迎面驶来的汽笛声和离你远去的汽笛声是一样的D.只有声波才能发生多普勒效应 答案：解析：若发生多普勒效应，则波源的频率不改变，A选项错误，若你以声波的速度随同某一个波峰一起远离声源，你将听不到声音，B选项正确，你听到迎面驶来的汽笛声的音调变高，而离你远去的汽笛声音调变低，C选项错误，多普勒效应是波动过程共有的特征，只要是波都可以发生，D选项错误.答案：BHi, everyone. I’m Jack____I’m twelve years old. I live with____parents in a big city. My father is____manager. He works at a hotel. My____is a teacher. She teaches history. It is my favourite____. I’m a student in Grade 7. I like playing basketball. Sometimes I play____inthe playground in the morning. That starts a____day for me. Sometimes you can____me there after school. I have a rest (休息). And then I go home and do my homework.Today is my birthday. I get some books and pens from my friends. And I get a computer from my parents.____is it? Look! It’s____my desk.【1】A. but B. and C. so D. or【2】A. my B. your C. his D. her【3】A. the B. an C. a D. 不填【4】A. mother B. grandfather C. brother D. sister【5】A. teacher B. subject C. sport D. school【6】A. them B. this C. it D. these【7】A. cool B. bad C. funny D. new【8】A. draw B. meet C. thank D. help【9】A. Who B. Where C. How D. What【10】A. over B. about C. on D. for