试述使用XD-22A型低频信号发生器产生一个频率为5khz、电压值为10mV(有效值

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问题:

试述使用XD-22A型低频信号发生器产生一个频率为5khz、电压值为10mV(有效值)正弦信号的调节过程。

考点:动力与电气工程电子测量电子测量题库
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下列电流值中,最小的是(   )
A.0.4 A    

B.0.5×105μ A   

C.480mA    

D.9.6×10 -4A

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短文填空(10分)
根据短文内容,从方框中选择合适的单词并用其正确的形式填空,使短文意思完整、正确。(每空一词,每个词只能使用一次,有两个多余词)。
beautiful  same classroom  deeply(深深地)   friend  classmate  do  know     look  anything  because   success
My teachers thought I was the worst student. My family also had the 小题1:thought as my teachers.
When I was going to give up my study, a new teacher, Miss White, came to our school. She was young, 小题2:and knowledgeable(知识渊博的).
One day, I was sitting alone in my 小题3:, Miss White came up to me and talked to me happily. Soon her smile swept away my unhappiness.
“Do you think I can go to college?” I didn’t 小题4:why I asked such a question. I thought she must say “no” 小题5:everyone else said so. But she said, “Dear, you can do 小题6:you want. Just try, and you’ll get closer to success. I believe you are the best!”
I was touched  小题7:  by her words. I decided to study hard. From then on, we became good 小题8: She often helped me with my study in her free time.
In the end, I  小题9: well in my studies and went to a good college. Miss White is an angel (天使).Her words have kept me going forward. She helped me to see that I am special and I can be  小题10: in life.
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急性喉炎是喉部黏膜及喉部软骨的急性卡他性炎症。

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在义齿重衬前不必特别注意的是()。

A.义齿的正中关系是否正确

B.义齿的非正中关系有无干扰

C.在重衬前适当的选磨调

D.患者的牙槽骨有无吸收

E.义齿戴用时有无疼痛和黏膜破溃

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下列关于变异的叙述中,不正确的是()

A.生物所发生的基因突变一般是有害的,因此基因突变不利于生物的进化

B.基因重组只能产生新基因型,而不能产生新的基因,基因突变才能产生新的基因

C.生物变异的根本来源是基因突变

D.自然状态下的突变是不定向的

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