题目

Today is Tuesday morning. Look at Kate's schedule. Monday10-a.m.- -visit mother changed to WednesdayTuesdaymorning - buy tickets for music concertsend parcel (包裹) to the USAWednesdayShopping leave until Thursdayvisit mother (all day)Thursdayimportant - pay electricity billFriday2:00 p:m meet Alfred -in the perkCancelled! Alfred will call next week. 【1】On Friday, Kate will ________.A.meet Alfred B.not go to the park C.call Alfred【2】From Kate's schedule, we learn that ________.A.She stayed with her mother on MondayB.She is going to the USA on TuesdayC.She isn't going shopping until图为示波管的示意图，竖直偏转电极的极板长l＝4.0 cm，两板间距离d＝1.0 cm，极板右端与荧光屏的距离L＝18 cm。由阴极发出的电子经电场加速后，以v=1.6×107 m／s的速度沿中心线进入竖直偏转电场。若电子由阴极逸出时的初速度、电子所受重力及电子之间的相互作用力可忽略不计，已知电子的电荷量e＝1.6×10-19 C，质量m＝0.91×10-30 kg。小题1:求加速电压U0的大小；小题2:要使电子束不打在偏转电极的极板上，求加在竖直偏转电极上的电压应满足的条件；小题3:在竖直偏转电极上加u＝40 sin100πt（V）的交变电压，求电子打在荧光屏上亮线的长度。