【单选题】Do you know _____ this time yesterday? [ ]
B.
who they are waiting for
D.
who they were waiting for
【单选题】—Who are they? — ______ . [ ]
【单选题】Who are they?______father and mother . [ ]
【单选题】Who are they ?
B.
They are in front of the door .
C.
They are my grandfather and grandmother .
【多选题】RC振荡器工作原理与LC振荡器类似,只是用RC选频网络代替LC回路,适于较低的振荡频率,
A.
若放大器为同相放大器,则RC选频网络提供的反馈系数应为正实数
B.
若放大器为反相放大器,则RC选频网络提供的反馈系数应为负实数
C.
依然应该满足反馈型振荡器的起振、平衡和稳定条件
D.
在电容C可变范围一定时,文氏电桥振荡器的可调节频率范围小于LC振荡器
【单选题】________ paresseux qu'il ait été, il a réussi à l'examen final