—Talking on WeChat .people's way of communicating in the recent few years.
A:influences
B:influenced
C:is influencing
D:has influenced
如图所示,电磁铁的左下方有一铁块,在弹簧测力计作用下向右作匀速直线运动.当铁块从电磁铁的左下方运动到正下方过程中,同时滑片逐渐向上滑动,下列判断正确的是( )