【简答题】A:WHAT IS IMPORTANT WHEN…? Aiming to improve career prospects ?Reading business articles ?Learning a foreign language ? B:WHAT IS IMPORTANT WHEN…? Deciding how to transport goods ?Destination ?Speed &...
【单选题】The navigable semicircle of a tropical storm in the South Indian Ocean is located on which side of the storm’s track? ()
【简答题】已知掺铒光纤放大器中铒离子浓度n=2×1018cm-3,σ12(v)=σ21(v)=2×10-21cm2,σ13(vp)=4×10-21cm2,l=15m。当输入泵浦光功率Pp0=100mW时放大器的小信号增益GdB0=0dB,试求Pp0=100mW时光纤放大器的小信号增益(以dB为单位)。
【简答题】化简: 2 x 2 3 y 2 ? 5y 6x ÷ 10y 21 x 2 .