... Named the “Father of Traffic Safety,” Eno developed the first traffic plans for major cities including New York, London, and Paris, and is credited with helping to invent and popularize [r] ...
... 3.已知命题 p :角 的终边在直线 y 3 x 上,命题 q : k 3 k Z ,那么 p 是 q 的( ) A. 充分不必要条件 B. 必要不充分条件 C. 充分必要条件 D. 既不充分又不必要条件 4.若 a 1,0 c b 1 ,则下列不等式不正确的是( ) ...
... C.物体 B 对斜面的作用力减小 D.地面受到的摩擦力大小可能变大 21.如图所示是导轨式电磁炮的原理结构示意图。两根平行长直金属导轨沿水平方向固定, 其间安放炮弹。炮弹可沿导轨无摩擦滑行,且始终与导轨保持良好接触。内阻为 r 可控 电源提供的强大恒定电流从一根导轨流入,经过炮弹,再从另一导轨流回电源,炮弹被 导轨中的电流形成的磁场推动而发射。在发射过程中,该磁场在炮弹所在位置始终可以 简化为磁感应强度为 B ...
... W: On the way home from my business trip, I’ll be in Paris for twenty-four hours. Do you have any suggestions about what I should do? M: Oh, that’s so little time! Well, since it’s all you have, you should rent a bike. ...