RC相移振荡器是用三级RC相移电路使输出信号相移（）后进入放大器_爱下问搜题

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问题单项选择题

RC相移振荡器是用三级RC相移电路使输出信号相移（）后进入放大器输入端时，由于共发射极放大器输出信号与输入信号反相，因此产生正反馈，满足振荡条件。

A.90°

B.180°

C.120°

D.270°

答案

参考答案：B

选择题

(2013·合肥模拟)—　　　　bargaining is so interesting?

—Sometimes it is a test to see who can stand their ground for the longest.

A．What is it that

B．Why is it that

C．What it is that

D．Why it is that

单项选择题

以下（）不属于海难事故。

A.爆炸

B.船体破损

C.船体颠簸