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【简答题】
现有电路如下: A . RC 桥式正弦波振荡电路 B . LC 正弦波振荡电路 C .石英晶体正弦波振荡电路 选择合适答案填入空内,只需填入 A 、 B 或 C 。 (1) 制作频率为 20 Hz ~ 20 kHz 的音频信号发生电路,用 。 (2) 制作频率为 2 ~ 20 MHz 的接收机的本机振荡器,用 。 (3) 制作频率非常稳定的测试用信号源,用 。
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【简答题】Anthropologists agree that our primitive ancestors who inhabited the tropics probably have natural protection against the sun.
【单选题】Many people have made a _____ to a physical fitness program so as to maintain good health .
A.
decision
B.
commitment
C.
contribution
D.
difference
【简答题】It ’s excited that so many people like that exciting TV program. A B C D _____________
【单选题】All the students are required to attend the two-day( )program so that they can have a complete understanding of the university they are admitted to.
A.
orientation
B.
accomplishment
C.
enthusiasm
D.
independence
【单选题】The reason for the government's expansion program working not so well is______
A.
because the farmers were uncertain about the financial support the government guaranteed
B.
because the farmers were uncertain about the benefits of expanding production
C.
because the farmers were uncertain whether foreign markets could be found for their produce
D.
because the older generation of farmers were strongly against the program
【单选题】Our taste for fat and sugar appears to have______ from our ancestors.
A.
carried
B.
stemmed
C.
succeeded
D.
rooted
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