A:how can I get to your school
B:how much it costs to get to your school
C:how far it is from your home to your school
D:how long does it take me to get to your school
如图1所示,一个匝数n=100的圆形线圈,面积S1=0.5m2,电阻r=1Ω.在线圈中存在面积S2=0.4m2、垂直线圈平面(指向纸外)的匀强磁场区域,磁感应强度B随时间t变化的关系如图2所示.将其两端a、b与一个R=2Ω的电阻相连接.试求:
最先证明地球形状的事件是( )
—Really? Who will _______ it?