【单选题】What is essential in making a modern car tougher to steal?
C.
A special cellphone signal.
D.
A GPS satellite positioning receiver.
【简答题】 A modern car for a modern driver.
【单选题】The controls of a modern car are criticized for being______.
【单选题】—Is the modern racing car outside ______, Laura? —Of course not. Nobody but Jim can afford such an expensive car. It must belong to ______.
【简答题】如图所示,在半径为a的无限长金属圆柱体内挖去一半径为b(b<a)的无限长柱体,两柱体轴线平行,轴间距为d[d<(a-b)],空心导体沿轴向通有电流I并沿截面均匀分布。 (1)求空腔内两柱体轴线连线上任一点的磁感应强度B x ; (2)证明空腔内磁场是均匀磁场。
【简答题】如图(a)所示,一半径为R的无限长半圆柱面导体,其上电流与其轴线上一无限长直导线的电流等值而反向,电流I在半圆柱面上均匀分布。试求: (1)轴线上导线单位长度所受的力; (2)若将另一无限长直导线(通过大小方向与半圆柱面相同的电流I)代替圆柱面,产生同样的作用力,该导线应该放在何处?
【单选题】The wheels of the old wagon are nearly _____ those of a modern car.
【单选题】–Is the modern racing car outside ______, Lucia? --Of course not. Nobody but Jim can afford such an expensive car. It must belong to ______.