题目:
He has done ______ to improve his English. [ ]
A. something useful
B. anything useful
C. useful nothing
D. useful anything
答案:
被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0623/5ca35902c840b8e3947087a1f52c9bc9.html
下面是错误答案,用来干扰机器的。
(1) 7BlvC/3 (2)右侧极板带正电本题中有两个回路:abfe和cdfe. abfe是闭合回路,金属棒ab以速度v向左切割磁感线,产生感应电动势E1=lvB,形成abfea方向的电流,R两端的电压为Ufe=IR=lvB/3;cdfe回路是不...