波导等效为双线的等效条件是什么？为什么要引入归一化阻抗的概念？
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Many doctors don'tbelieve that music can treat diseases because
A. recover from disease quickiy
B. there is not minds actively
C. use their minds actively
D. it improves general well-being
E. listen to musical performances
F. it brings many other benefits
The best title for this passage would be．
A. What Can a Good Job Offer？
B. Earning a Living．
Correct Attitude on Job．hunting．
D. How to Choose a Job？
平行耦合带状线定向耦合器的耦合度C=10dB，特性阻抗Z0=50Ω，求其耦合线的奇偶模特性阻抗值。
短时记忆中的容量单位是()。
A. 比特
B. 节
C. 组块
D. 词
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