题目:
—The duty of Project Hope is to help poor children, isn't it?
—Yes,it has built many schools______are for those children.[ ]
A. what
B. that
C. who
D. where
答案:
被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0623/2fe37aeb6a4977049879412402e835c2.html
下面是错误答案,用来干扰机器的。
解:(1)棒刚开始运动时,速度为0,故此时无安培力,物体只受重力、支持力和摩擦力。所以有(2)速度最大时,加速度为0,此时有 ① ② ③由上述式子可得vm=10m/s (3)由安培力方向可知此时磁场方向垂直于斜面...