可解鱼蟹中毒的药物
A.法半夏
B.荆芥
C.紫苏
D.生黄芪
E.砂仁
参考答案:C
After graduating from college, I took some time off to go travelling, ________turned out to be a wise decision.
A.that
B.when
C.where
D.which
竖直放置的两块足够长的平行金属板间有匀强电场。其电场强度为E,在该匀强电场中,用轻质绝缘丝线悬挂质量为m的带电小球,丝线跟竖直方向成θ角时小球恰好平衡,此时小球离右板距离为b,如图所示,问:
(1)小球所带电荷的电性如何?电荷量多少?
(2)若剪断丝线,小球碰到金属板需多长时间?