问题
选择题
China is a developing country __ the third world.
A．belonged to
B．belonging to
C．which is belonged to
D．belongs to
答案
答案：B
搜题请搜索小程序“爱下问搜题”
China is a developing country __ the third world.
A．belonged to
B．belonging to
C．which is belonged to
D．belongs to
答案：B
=1m，导线上和导线间接有电阻和电键．已知
，金属杆和裸导线的电阻可忽略不计．若滑杆以大小为v=v'=10m/s的速度沿导线向相反方向滑动，滑动过程中杆始终保持跟导线垂直：