立体几何建立坐标系

已知钡的活动性介于钾和钠之间,则下述说法可能实现的是（ ）A.钡可从氯化钠溶液中置换出钠 B.钡可从冷水中置换出氢C.钡能从氯化钾溶液中置换出钾 D.钡与水反应比钾与水反应剧烈每个选 描写春风春雨变化特点的写景作文(350字）各位知识分子,请你们在5分钟之后给我答复, 山行作者写景的视角有什么变化? 小溪哗哗地流着.（改成拟人句） 描写春雨变化特点的写景作文（350字）里面要有春雨的变化哦!请在5分钟后给我答复, 帮忙从写景特征,意境,情感,写景角度,和写作手法五个角度赏析滕王阁序, 钠钾铜钡为什么不能把后面的金属置换出来 把标有12V3W和12V4.5瓦的两个灯泡并联接到12V的电源上,若通过两个灯电量之和为2库仑,则电流做的功为多少可提供选项：A、2J B、7.5J C、15J D、24J请在回答后给详细过程，辛苦大家 had you ever seen any films starring zhangziyiShe had attended the China Central Drama College, _______ dance before she became an actress. A Studying Bstudied为什么选A Is 什么Zhang Ziyi 23317(zhang)：some departments have been know to drop or curtail funding for students starting with the fourth year of graduate study.想知道本句翻译及语言点1_some departments have been known to drop or curtail funding for students startin 为什么由二叉树的中序序列及前序序列唯一确定二叉树?为什么由后序和中序就不能?解释一下可以倒是可以确定,我的意思是为什么由前序和中序确定的就是唯一的? 将标有6v3w字样的小灯泡接到3v的电路中,消耗的功率是多少瓦 I believe that love means that you can take it up and put it down,ie.even if you lose the love,求中文. she is rich() however,she does not feel happy标点符号逗号分号冒号句号 那个可以用那个不能用.求仔细思考she is rich() however,she does not feel happy就是在括号内填上合适的标点符号啦 Working as she does翻译 i say my heart sad down....then i ill lost my mind ,just that.这句话的意思是什么?求...i say my heart sad down....then i ill lost my mind ,just that.这句话的意思是什么?求翻译中文, how did lisa feel when she saw the how she feel?if i send a massage to her, she don't know me,will she reply me? was,street,elephants,see,fun,down,so,the,marching,many,to,it连词成句 ___great fun it was__so many elephants marching along the streetA how ; to see B what a ; seeing C What ; to see D How; seeing Tourist saw many elephants marching down the street.改成被动句 many people fly to thailand to have fun with the elephants 同义句 钢化玻璃平面度一般是多少 平面度误差的评定方法有几种? 一个线圈的自感系数为0.5H,电阻可以忽略,把它接在频率为50hz,电压为220v的交流电源上,求通过线圈的电流.若以电压作为参考相量,写出电流瞬时值的表达式,并画出电压和电流的相量图 将电阻为6??.5mH的线圈接在220V的电源上,计算电源频率为50Hz时的（1）感抗与电阻；（2）电流（3）有功功率,无功功率及视在功率 半导体技术经历的几个阶段 什么叫半导体掺杂技术?要是想使原本只能被能量高于紫外线的光激发的物质,也能被能量小于紫外线的光激发,这有可能通过半导体掺杂技术改性被激发物质来实现吗?但我还想知道：要是想使 半导体技术哪个国家的最好? 什么是半导体离子注入技术? you look so