问题
名词解释
脉冲下降时间tf
答案
参考答案:脉冲波从0.9Um下降到0.1Um所经历的时间。
脉冲下降时间tf
参考答案:脉冲波从0.9Um下降到0.1Um所经历的时间。
Selina, Michael, Tony and Sam enjoy listening to the radio. Read the following description and help them make proper choices. 57. ________ Tony, a sports lover, always cares much about sports events. He dreams to be a sports reporter after graduation. 58. ________ Michael is a university student. He likes music very much, especially rock and pop music. 59. ________ Sam is a teacher. He is one of the most popular teachers, because he always likes to tell his students what is going on world widely. So he needs to know global events of all kinds. 60. ________ Selina has three children. They are very lovely. They are interested in drama, reading and watching TV as well.
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