【判断题】【消耗次数：1】
低频信号发生器主振级主要采用文氏桥振荡器，电路中常采用负温度系数的热敏电阻以促进振荡器起振和稳定输出信号幅度。
①
正确
②
错误
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相关题目
【简答题】
试用555多谐振荡器构成简易温度报警器
【单选题】
信号发生器的基本组成：_______、______和 _______、_______。
①
转换器、变换器、输出电路、振荡器
②
测量器、振荡器、变换器、输出电路
③
振荡器、变换器、输入电路、振荡器
④
振荡器、变换器、输出电路、振荡器
随机题目
【单选题】
3.This little girl began to show the sign of ______ her brother in spoken English.
①
better
②
surpassing
③
exceeding
④
beyond
【单选题】
8. As a part of______ process, gradual loss of hearing ability can be difficult to deal with.
①
aging
②
aged
③
old
④
elderly
【单选题】
5.Sometimes animals can _______ the coming disaster, so they can protect themselves.
①
imagine
②
taste
③
sense
④
ignore
【单选题】
13.Oil floats if you ______it on water.
①
will pour
②
are going to pour
③
pour
④
poured
【单选题】
22. When a fire ______ at the National Exhibition in London, at least ten priceless paintings were completely destroyed.
①
broke off
②
broke out
③
broke down
④
broke up
【单选题】
23. Realizing that he hadnt enough money and ______ to borrow from his father, he decided to sell his watch.
①
not wanted
②
not to want
③
not wanting
④
. wanting not
【单选题】
20.The girl’s voice was so low that we could ________ hear her.
①
seldom
②
almost
③
only
④
hardly
【单选题】
7.When we go abroad we are always being ______ around like a group of mentally disabled people.
①
guided
②
.ushered
③
introduced
④
displayed
【单选题】
9. All correspondence ______ to the editor should be sent by airmail.
①
addressed
②
sent
③
signaled
④
went
【单选题】
11.Since family ______children’s character, he encouraged parents to teach children reading.
①
formed
②
shaped
③
built
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made