It's difficult to choose!

相关推荐

• telegrapher's equation是什么意思
• language是不可数名词?she"s spent a lot of time learning the language ,so now she can speak(a few) little？可数的不是应该用a 不可数才用a little?
• FeS的电离中c(Fe+)*c(s2-)=6.25*10^-18,又知溶液中,[c(H+)]^2*c(S2-)=1*10^-22现将适量的FeS,投入饱和溶液中,要使溶液的c(Fe2+)达到1mol/L,应调节溶液的PH为多少?
• 填标点⑨听了这番有趣的解释,我对这种树木产生出一种sǜ rán qǐ jìng ( )的感情.它既能生在土质肥沃□气候相宜的美丽风景区□又能繁殖于干燥贫瘠□漫漫沙流的不毛之地□它在湖光山影□花红柳绿的秀丽处所□风姿飘洒□落落大方□现出一派bǜ bēi bǜ kàng( )的仪表□它在满目黄沙□寸草不生的古漠□轻声慢语□谦和内秀□没有一点傲然超众□gū fāng zì shǎng( )的神情□我爱旅行家树的所有具有的这种品质□离开非洲时,我曾想带回一株旅行家树的幼苗,移植于自己的庭院里,后来又作罢,心想：倒莫如把旅行家树的品质,移植于自心中.
• FeS饱和溶液中c(Fe2+)c(S2与c（H+）*c(OH-)=Kw类似,FeS饱和溶液中c（Fe2+)*c(S2-)=Ksp.常温下Ksp=8.1*10-17.理论上FeS的溶解度为?而事实上其浓度远大于这个数值,其原因可能是?
• Fe2+和S2-反应是生成FeS还是发生双水解?Fe2+和S2-反应是生成FeS沉淀还是发生双水解生成Fe(OH)2和H2S?为什么不发生双水解?FeS溶解度小于Fe(OH)2,H2S会和Fe(OH)2反应生成FeS?
• 1、登一座山,上山时每分钟行50米,到山顶后沿原路下山每分钟行90米,若上山所需时间比下山多400分钟,则这条山路有多少千米?2、甲、乙两人从A地出发,如果甲先走1消失,乙从后面追赶X小时后,刚好在B地追上甲,则甲走了多少小时?若甲的速度是6千米/时,乙的速度是8千米/时,则可列出的方程是_________?（用方程解答）3、轮船在两码头之间航行,顺水速度为a千米/时,逆水速度为b千米/时,则水流速度是多少千米/时?4、汽车以每小时72km的速度笔直的开向寂静的山谷,驾驶员按一声喇叭,4s后听到回想,已知声音在空气中的传播速度是340m/s,听到回响时汽车离山谷的距离是多少米?不懂。请用方程解答
• 已知数列（AN）是等差数列,是其前N项的和,求证：S6,S12-S6,S18-12成等差数列.设K为N*,Sk,S2k-Sk,S3k-S2k成等差数列吗?
• 阅读选择：We have a nice classroom.The windows are big and the wals are white.There's a bigblackboard on the front wall.A big desk is near it.It is for our teachers.There's a map of China and some other pictures on the wall.There are forty small desks and chairs in the room.They are for students.There are sixteen girls and twenty-four boys in our class.There are some flowers on the teacher's desk.They're for our English teacher.She is  a good teacher and w
• “Next Tuesday is going to be a holiday,”says the teache阅读理解“Next Tuesday is going to be a holiday,”says the teacher.“I want you to tell me what you are going to do,Terra.” “I’m going to the movie theater to see a movie,”says Terra.“It is a comedy about a fat professor.My classmates say it’s really funny.” “Anything else are you going to do?”the teacher asks.“Of course I’m going to do my lessons.I’mgoing to study math and physics in the morning.” “Do y
• 1 x的平方-4xy+4y的平方-x+2y-6
• 1.分解因式； （x-1)(x-2)(x-3)(x-4)-120