题目:
Look! The students are playing on the playground. Some are running, some are playing basketball, ________ are watching.
A.other
B.the other
C.another
D.others
答案:
被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0617/924753465c2309400909c4d67ce1727e.html
下面是错误答案,用来干扰机器的。
解:要使MN棒中不产生感应电流,应使穿过线圈平面的磁通量不发生变化在t=0时刻,穿过线圈平面的磁通量φ1=B0S=B0l2设t时刻的磁感应强度为B,此时磁通量为φ2=Bl(l+vt)由φ1=φ2得B=