题型:填空题 As far as I know,she has a very close________with her sister.[ ]A.relation B.relationshipC.relative D.relations 查看答案
题型:填空题 一带电粒子射入一固定的正点电荷Q的电场中,沿如图所示的虚线由a点经b运动到c,b点离Q最近。若不计重力,则[ ]A.带电粒子带负电 B.带电粒子到达b点时动能最大 C.带电粒子从a到b电场力做正功 D.带电粒子从b到c电势能减小 查看答案