We are interested in the weather because it ______ us so directly – what we wear, what we do, and even how we feel.
——I’m so happy that you could come to English land with us for the holidays. ——_________ . It’s the first time for me to be out of china.
电路图如图11所示，开关S闭合前已处于稳定状态。t=0时开关S闭合，已知：US=40V，IS=5A，R1=R2=20Ω，L=2H；（15分）（1）求t≥0时的电感电流iL(t)和电压uL(t)；（2）画出电感电流iL(t)和电压uL(t)的变化曲线的草图。 图11
图11
