问题
名词解释
压电效应
答案
参考答案：
对石英、酒石酸钾钠等晶体的表面施加压力，在两受力面上将产生异性电荷，形成电位差，反之这些晶体处于交变的电场内将产生振动，这种现象叫压电效应。工业上如压电效应型超声波发生器、晶体相声器等就是应用压电效应这一原理制成的。
搜题请搜索小程序“爱下问搜题”
压电效应
参考答案：
对石英、酒石酸钾钠等晶体的表面施加压力，在两受力面上将产生异性电荷，形成电位差，反之这些晶体处于交变的电场内将产生振动，这种现象叫压电效应。工业上如压电效应型超声波发生器、晶体相声器等就是应用压电效应这一原理制成的。
用所给词的正确形式填空（15分）
I have never _小题4:_____ that I will be a teacher one day. I am a shy girl and I am afraid of __小题5:______ before many people. I do not know ____小题6:___ to say. But I will be a teacher tomorrow morning! I made this _小题7:_______ just two weeks ago. Miss Williams, my English teacher, told me there was a teacher job, just for two weeks in this summer. She asked if I ___小题8:____ be interested. I wanted to make some money, so I __小题9:____ “yes” to her. At once I regretted but it was too late to ___小题10:___ my word back. There are about twenty foreign boys and girls in the class. They know very little English. I have ___小题11:_____ read the book that Williams gave me. Four of the lessons are very simple, in ___小题12:____ too simple. I do not know what to do _小题13:_____ these __小题14:____ simple words and sentences. I will read the lesson to them , and ask them to read after me, and then ask them to read it _小题15:_____. That will be about ten minutes, what shall I do next ? |