如图9-3所示，非周期信号的时域描述形式为（）。 A: u（t）=［10×1（t-3）-10×1（t-6）]V B: u（t）=［3×1（t-3）-10×1（t-6）]V C: u（t）=［3×1（t-3）-6×1（t-6）]V D: u（t）=［10×1（t-3）-6×1（t-6）]V

We should put the ______of subject under sunlights when we take photos under short lighting. A: 1/2 B: 1/4 C: 1/3 D: 1/6

$u$, $v\in E^3$, $u=(0,-1,1),v=(1,-1,-1)$. What is $||u \times v||^2$:<br/>______

$u$, $v\in E^3$, $u=(0,-1,1),v=(1,-1,-1)$. What is $\langle{u,v}\rangle$:<br/>______

$u$, $v$ and $w \in E^3$, $u=(0,-1,1),v=(1,-1,-1),w=(1,1,1)$. What is $(u,v,w)$:<br/>______

We would not have been [u]      [/u] if we had first met in our freshman year. A: compatible B: compatibly C: commonly

1. For example, when we pronounce / u / and / u: /, / u / is a short vowel, while / u: / is a long vowel, they are two different_______________.

连词成句 1 and 2 where 3 shall 4 meet5 we 6 when

二极管的端电压为U ,则二极管的电流方程是( )。 A: I S e U B: S e T U nU I C: S (e 1)T U n U I - D: S (e 1)T U nU I +

空气平行板电容器充电后与电源断开，然后充满各向同性的均匀电介质，则电容C，电容器的电压U，电容器的电场能量We和充入电介质前相比的变化情况是 A: C减小，U增大，We增大 B: C增大，U减小，We减小 C: C增大，U增大，We减小 D: C增大，U增大，We增大