在光滑的水平面上方，有两个磁感应强度大小均为B，方向相反的水平匀强磁场，如图所示PQ两个磁场的边界，磁场范围足够大。一个边长为a、质量为m、电阻为R的金属正方形线框，以速度v垂直磁场方向从如图实线位置开始向右运动，当线框运动到分别有一半面积在两个磁场中时，线框的速度为v/2，则下列说法正确的是
She______(watch)TVeveryevening.
()Thereare_____onthetable.
What'sthatman?
()1.Couldyouhelpme，please?A.OK.
()2.Thanksalot.B.You'rewelcome.
()3.Let'sputthebooksinthebox.C.It'sMonday.
()4.Canyoucarryit?D.No，it'sfull.
()5.Who'sondutytoday?E.lam.
()6.Isitempty?F.No，it'slight.
()7.Whatdayisittoday?G.Certainly.
()8.Isthatbagheavy?H.No.LiLeiisn'there..
()9.Areweallheretoday?I.No，thanks.
()10.Letmehelpyou.J.Yes，Ican.
