中速球跟高速球能用一根AB通讯线吗

将甲、乙两地间的距离看成1，设A从甲地出发到达乙地所用的时间为t ₁ ，B从甲地出发到达乙地所用的时间为t ₂ ，则
t ₂ =
3
V 1 + V 2 + V 3 ；t ₁ =
1
3 V 1 +
1
3 V 2 +
1
3 V 3 =
V 2 V 3 + V 1 V 2 + V 1 V 3
3 V 1 V 2 V 3 ；
t ₁ -t ₂ =
V 2 V 3 + V 1 V 2 + V 1 V 3
3 V 1 V 2 V 3 -
3
V 1 + V 2 + V 3 =
(V 2 V 3 + V 1 V 2 + V 1 V 3 )×( V 1 + V 2 + V 3 )-9 V 1 V 2 V 3
3 V 1 V 2 V 3 ( V 1 + V 2 + V 3 ) =

V 22 V 3 + V 2
V 23 +
V 21 V 2 + V 1
V 22 +
V 21 V 3 + V 1
V 23 -6 V 1 V 2 V 3
3 V 1 V 2 V 3 ( V 1 + V 2 + V 3 ) ；
因为V ₁ ＞V ₂ ＞V ₃ ；所以V ₂ ² V ₃ ＞V ₁ V ₂ V ₃ ；V ₁ ² V ₂ ＞V ₁ V ₂ V ₃ ；V ₁ V ₂ ² ＞V ₁ V ₂ V ₃ ；V ₁ ² V ₃ ＞V ₁ V ₂ V ₃ ；
所以t ₁ -t ₂ ＞0；
所以A车用的时间多，B车先到达．
故选B．

轮船在静水中速x
4(2+x)=5(x-2)
8+4x=5x-10
5x-4x=8+10
x=18
18+2＝20
答：顺水速度20千米/小时

电子绕原子核的运动可以说明其波动性,电子在核外的运动并不是经典意义上的圆周运动,而是表现为电子云的形式,在有些地方出现的概率大一点,有些地方小.另外电子的衍射实验也可以说明其波动性,不过要有到晶体利用晶体的晶格才能观察到其衍射.
晶格的尺寸在10^-10m左右,这也说明电子波的波长很短,电子波也不是电磁波等经典意义上的波,而是一种概率波.
就你举的电子显像管的例子,你可以用以下方式计算出电子波的波长.首先电子的能量E=eU,其中e是电子的电量.然后P^2=2mE,其中P为电子动量,m为电子质量,由此可以计算出电子动量.再根据德布罗意公式h/λ=P,其中h为普朗克常量,λ为电子波长.
由以上关系式可见动量越小,电子波长越小.电子通过1000伏的电场获得的能量是很小的,所以其电子波的波长也微不足道,在显像管里更明显的是表现出粒子性.

由于10个节拍为8S
所以一个节拍的时间t=8s/10=0.8s
而跑步正好用了9个节拍
所以跑步用时T=0.8s*9=7.2s
所以平均速度v=s/T=60m/7.2s=5/6m/s≈8.33m/s

假设船的速度是1,那么贾的速度就是1.12,乙的速度是0.88.两船相向而行,第一次相遇,时间相等,那么它们的行程之比就是速度之比.所以甲的行程所占百分比就是1.12/(1.12+0.88)=0.556=%55.6.

滤孔的大小有区别,慢速的细,快速的孔大.滤纸的盒子后面有对应的表格.你可以去看下.
主要就是根据你需要过滤的东西来选择滤纸了.一般最常用的是定性中速.

解题思路：整个圆表示该市交通事故的总数，统计图只能说明在该市中等速度行驶的交通事故比超速行驶的交通事故数量多，并不能说明超速行驶比中等速度行驶安全．因为绝大多数人都以中等速度开车，发生事故的基数大，只有极少数人违章超速行驶，发生事故的总数自然比中等速度行驶的要少些．

要比较超速行驶和中等速度行驶谁安全些，应该比较它们在这两种情况下的事故发生率，例如，在中等速度行驶的10000人中，发生事故70起，事故发生率为0.7%，在超速行驶的100人中，发生事故30起，事故发生率为30%，远远高于中速行驶的事故发生率，但如果采用上面的数据处理方法和数据呈现方式，就容易给人以误导．

点评：
本题考点： 扇形统计图；从统计图表中获取信息．

考点点评： 关键明白，中等速度开车的人多，发生事故的基数也就大，超速开车的人少，发生事故的基数也就小．

不可以,分析事故是要考虑整个情况,也就是说正常速度行驶下发生事故的占正常速度行驶下的总比例,超速行驶下发生事故的占超速行驶下的总比例.这时你会发现70%会大大减少,而30%可能会增加.

每过30分钟就休息15分钟靠岸,每次行驶按45分钟算,则一共休息3次,实际行驶时间为90分钟,设小艇最大距离为X,则有X/(3+1.4)+X/(3-1.4)=1.5,解得X=1.76

假设船的速度是1,那么贾的速度就是1.12,乙的速度是0.88.两船相向而行,第一次相遇,时间相等,那么它们的行程之比就是速度之比.所以甲的行程所占百分比就是1.12/(1.12+0.88)=0.556=%55.6.

open~~
medium,中等的意思~~

我们老师说100呦,可是我觉得要准备150的内,充分嘛

船在静水中速度为x,水流速度y
24/（x+y）+24/（x-y）=2
8/（x+y）+18/（x-y）=1
解得（x-y）大于（x+y）
跟题意不附
所以题目不对
顺水航行18千米,逆水航行8千米,共用1小时,还差不多
24/（x+y）+24/（x-y）=2
18/（x+y）+8/（x-y）=1
解得x=5y 得入24/（x+y）+24/（x-y）=2
解得y=5 x=25

用一个三元一次方程就可以解出来的,说实在的那个假设有点儿玄妙

1:、 56种
2、（2+i）/i=1-2i 虚部为-2i.
3、公差为1. 即1,2,3,4…………
4、等于2
5、b²／a²

题目中没有交代水流的方向,应有两种情况,但结果是一样的.我们假设去时是顺水.
行程分四阶段:①10:15~10:45,（15 ) ②11:00~11:30,(15) ③11:45~12:15,(15) ④12:30~13:00
根据题意,①阶段去 (1.4+3)/2 = 2.2 km
③④阶段回(3-1.4)/2 *2 = 1.6 km 中间相差0.6km
设②阶段去用了t小时,1.6(0.5-t)-4.4t=0.6,t=1/30
也就是说在②阶段,旅游者行2分钟就必须返回.
这样他所行的最大行程是176/75km≈2.35km.
这道题的题目不错的话,答案“1.7”肯定不对!

按照孔隙的大小,滤纸可分为快速,中速和慢速3种.快速滤纸孔隙最大,慢速滤纸孔隙最小.
1.快速滤纸,因纸质疏松,斑点易扩散,适合于Rf值较大的样品和粘度较大的展开剂
2．慢速滤纸,斑点不易扩散,适合于Rf值较小的样品和粘度较小的展开剂,但展开时间较长
3.中速滤纸界于两者之间
颜色区别：
定量滤纸：
快速：黑色或白色纸带
中速：蓝色纸带
慢速：红色或橙色纸带
定性滤纸：
快速：黑色或白色纸带
中速：蓝色纸带
慢速：红色或橙色纸带

定性滤纸的孔径是不规律的,通常定性滤纸的孔隙大,定量的小.滤纸滤过速度的不同,孔径也不同.一般定性滤纸孔径大而且也没有很严格的规定.定量滤纸分为快速、中速和慢速三种,其孔径分别大约是80～120微米、30～50微米、和1～3微米.

抽滤选择快速滤纸,因为抽主要靠滤饼过滤,阻力较大,为了迅速过滤选择快速滤纸.
自然过滤就用中速的,速度慢,容易形成滤饼,过滤效果较好.

"Le Yangyang" are the mascots for the 2010 Asian Games in Guangzhou. The mascot was released on Monday, April 28, 2008. (Photo credit: chinanews)Photo Gallery>>Five sporty goats, dubbed "Le Yangyang," will serve as the mascots of the 2010 Asian Games in Guangzhou.
The five goats, A Xiang, A He, A Ru, A Yi and Le Yangyang, are a play on Guangzhou's nickname, "City of Goats," China News Service reports.
The mascot design came from a legend about five immortals who took five goats to Guangzhou, each holding an ear of corn in its mouth. There, the immortals prayed for an end to famine, then flew into the sky as the five goats turned into fossils.
The Chinese character "yang" or "goat" is also an auspicious symbol. The mascot is believed to bring harmony, blessings, success and happiness to the Asian people.
Officials held a gala on Monday evening to mark the event in Guangzhou.
Referred to as the Asian Games Asian Games Asia's largest integrated Games held every four years term with the Olympic Games held in interphones. Initially sponsored by the Asian Games Federation in 1982 by hosting the Olympic Council of Asia. Since the beginning of the first session in 1951 has so far held 15 sessions. International Olympic Committee recognized the Asian Games as an official Games in Asia.
16th Asian Games in 2010 November 12-27 in Guangzhou China and Guangzhou is China's second city to obtain the right to host the Asian Games. Beijing had in 1990 held the 11th Asian Games. Guangzhou Asian Games will be located 41 events the history of the Asian Games are the largest events ever. Guangzhou Asian Games will be held after the Tenth Asian disabled.
March 2004 a total of four cities hosting the Asian Games: Guangzhou Kuala Lumpur Seoul (Seoul) Amman; but the other three bidding cities have decided to quit competing. July 1 2004 OCA announced that Canton was the right to host the 16th Asian Games.
Asian Games emblem on November 17 2006 Sun Year-end Memorial Hall in Guangzhou solemnly announced to the symbol of Guangzhou - "wuyang statue" as the main outline of the design patterns become the emblem of the 2010 Guangzhou Asian Games.
Apart from the Olympic Games has 28 the Asian Games there are 13 non-Olympic Games including the new Go wushu dragon boat and other Chinese traditional items.
November 26 2006 the Sixteenth Asian Games Organizing Committee was held in Guangzhou Zhongshan Memorial Hall in 2010 Asian Games emblem launch from Canton Zhangqiang designers design a symbol of "Guangzhou" Guangzhou has become the emblem design Guangzhou 2010 Asian Games emblem. The logo design to the increase in soft lines form a shape similar to the outline shape wuyang torch symbolizing the Asian Games torch burning and never extinguished. Embodies the symbol of Guangzhou city Guangzhou has also expressed the people's aspiration but also the performance of the Games should be dynamic.
Guangzhou Asian Games mascot named LeyYangyang a set of five kinds for the largest number of previous Asian Games mascot. "Wuyang" the city of Canton are the most famous a sign to five sheep as a mascot fully reflects the host country host city of the historical background spiritual outlook and cultural charm. It has five sheep with the Beijing Olympic mascots "Beijing welcomes you" similar name the image of sports are stylish five sheep respectively named "Xiang" "Ah and" "such as the Arab-Israeli" "Ah Yi" "LeYangyang" form a "harmonious smug music titled".expression of the people in Asia Guangzhou Asian Games will bring "good luck harmony happy successful and happy" the good wishes and also conveyed the current Games "harmony passion" philosophy.
Guangzhou Asian Games Mascot of creativity from the Canton city legend. It is said that a long time ago Canton had once occurred famine year after year people living in dire poverty. One day the sky has five immortal respectively Imago riding mouth of 5 cents sheep Canton come. Xianren the rice to the Guangzhou people and wish never famine here and five cents into a stone sheep to stay in Canton. From then on Guangzhou Lingnan into the most affluent places. Thousand years ago the "title wuyang Valley" legend making the "wuyang" has become the most famous city of Canton a sign
亚洲运动会简称亚运会,是亚洲地区规模最大的综合性运动会,每四年举办一届,与奥林匹克运动会相间举行.最初由亚洲运动会联合会主办,1982年后由亚洲奥林匹克理事会主办.自1951年第一届始,迄今共举办了15届.国际奥林匹克委员会承认亚洲运动会为正式的亚洲地区运动会.
第16届亚运会将于2010年11月12日至27日在中国广州进行,广州是中国第二个取得亚运会主办权的城市.北京曾于1990年举办第11届亚运会.广州亚运会将设41项比赛项目,是亚运会历史上比赛项目最多的一届.广州还将在亚运会后举办第十届残疾人亚运会.
2004年3月共有四座城市申办亚运会：广州、吉隆坡、汉城（首尔）、安曼；但之后其他三个申办城市相继决定退出竞逐.2004年7月1日,亚奥理事会宣布广州获得第十六届亚运会主办权.
亚运会会徽于2006年11月17日在广州孙中山纪念堂隆重揭晓,以广州的象征€€€€“五羊雕像”为主体轮廓设计的图案成为2010年广州亚运会会徽.
除了有28项奥运会比赛项目,该届亚运会还有13项非奥运会项目的正式比赛项目,其中包括新增设的围棋、2006年11月26日,第十六届亚运会组委会在广州中山纪念堂举行2010年亚运会会徽发布仪式,由广州设计师张强设计的象征“羊城”广州的会徽设计方案成为2010年广州亚运会会徽.该会徽设计以柔美上升的线条,构成了一个造型酷似火炬的五羊外形轮廓,象征着亚运会的圣火熊熊燃烧、永不熄灭.既体现了广州的城市象征,也表达了广州人民的美好愿望,还表现了运动会应有的动感.
武术、龙舟等中国传统项目.
广州亚运的吉祥物取名乐羊羊,一套5种,为历届亚运会中数量最多的吉祥物.“五羊”是广州市最为知名的一个标志,以五只羊作为吉祥物,充分体现了东道国、主办城市的历史底蕴、精神风貌和文化魅力.这五只羊有着与北京奥运会吉祥物“北京欢迎你”类似的名字,形象是运动时尚的五只羊,分别取名“阿祥 ”、“阿和”、“阿如”、“阿意”、“乐羊羊”,组成“祥和如意乐洋洋”,表达了广州亚运会将给亚洲人民带来“吉祥、和谐、幸福、圆满和快乐”的美好祝愿,也同时传达了本届运动会“和谐、激情”的理念.
如果觉得长自己删掉一些.

设轮船在静水中速度为X
则顺水速度是X+2,逆水速度是X-2
则有
(X+2)*3=(X-2)*4
3X+6=4X-8
X=14km/h

培养语感很重要,不管你现在能听懂多少,尽量去听,英语是日积月累的,时间长了会看到效果

Talking clock
会说话的钟
While proudly showing off his new apartment to friends,a college student led the way into the den."What is the big brass gong and hammer for?" one of his friends asked."That is the talking clock," the man replied."How's it work?"
"Watch," the man said and proceeded to give the gong an ear shattering pound with the hammer.Suddenly,someone screamed from the other side of the wall,"Knock it off,you idiot!It's two o'clock in the morning!"
一个学生带他朋友们参观他的新公寓,甚是得意.“那个大铜锣和锤子是干什么用的?”他的一个朋友问他.“那玩意儿厉害了,那是一个会说话的钟”,学生回答.“这钟怎么工作的”,他的朋友问.“看着,别眨眼了”,那学生走上前一把操起铜锣和锤子,拼命地敲了一下,声音震耳欲聋.突然,他们听到隔壁墙那边有人狂叫,“别敲了,你这白痴!现在是凌晨两点钟了!”
A GOVERNOR visiting a State prison was implored by a Convict to
pardon him.
"What are you in for?" asked the Governor.
"I held a high office," the Convict humbly replied,"and sold
subordinate appointments."
"Then I decline to interfere," said the Governor,with asperity; "a
man who abuses his office by making it serve a private end and
purvey a personal advantage is unfit to be free.By the way,Mr.
Warden," he added to that official,as the Convict slunk away,"in
appointing you to this position,I was given to understand that
your friends could make the Shikane county delegation to the next
State convention solid for - for the present Administration.Was I
rightly informed?"
"You were,sir."
"Very well,then,I will bid you good-day.Please be so good as to
appoint my nephew Night Chaplain and Reminder of Mothers and
Sisters."

设船速为X
0.75(X+3)=X-3
X=15KM/H

1.A 2.A和C(单选的话A) 3.D 4.A 5.D剩下的DAAADACBABBACAA

1.我游览了万里长城、故宫博物馆、秦始皇陵兵马俑和南京长江大桥等风景名胜.（南京长江大桥不是古迹）
2.驾驶员在长途行驶中应养成中速行驶,并注意中途停车让车胎降温的习惯.缺谓语

普通水,其后是糖水

Win Competition of Environment Protection for Beijing
Although the 2008 Olympics are still three years away,another special competition has already started in Beijing.This time,the competitors are not the athletes from all over the world,but the people living in Beijing.The special competition is not held in a stadium,but in every street and every corner of Beijing.I suppose some of you may have already guessed what the special competition is.Yes,it is the competition of protecting our environment and creating a green Beijing for the 2008 Olympic Games.
Someone may ask who is our rival in this competition?The modern Los Angeles,the charming Sydney,or the historic Athens?No,none of them.The real rival is ourselves.It is our bad habits of neglecting to protect environment in our daily life.
Several years ago,I was very lucky to have an opportunity to live in the United States for about two years.I not only enjoyed the beautiful environment there,but also appreciated the American people's active way of protecting their environment.Now,whenever the environment protection is mentioned,a beautiful view of California will arise in my mind:white clouds flying across the blue sky,green grassplot sprinkled with colorful flowers and small animals playing happily among the trees.
I remember that at the beginning of my coming to America,I often went to my father's working place,the United States Geological Survey,to have fun.Each time I found a lot of people riding bicycles to their offices.Among the cyclists,an old man with white hair attracted my attention.Curiously,I asked my father," Why does the old man ride his bike to work every day?Doesn't he have enough money to buy a car?" Father laughed,"No,not because of money.Actually,he is one of the greatest scientists in the world.He can afford to buy a motorcade if he likes.He is just an environmentalist and usually doesn't drive unless going shopping,or in bad weather.In America,there are a lot of environmentalists,who actively protect their environment.For example,in Palo Alto city we are living now,there is even a bicycle-to-work day on May 19th every year to encourage people to decrease air pollution caused by cars".
Later,I also learnt another interesting fact of environment protection there.In some states of America,in order to decrease air pollution,save energy and reduce traffic jams,state governments encourage people to take buses to work or to share a car among several people.They even set special "diamond lanes" in some main streets,which are only for the vehicles with 2 or more people.
The positive actions of American people and the effective measures the American government takes in environment protection fully won my respects and deeply affected my consciousness in environment protection.
When I was back in China,people often asked me:" What do you think of America?" I always bolt out:" Wonderful,especially the beautiful environment." Frankly speaking,after several years,the faces of my American teachers and friends have gradually faded away from my mind,but the blue sky,green grass and lovely animals in California often arise in my mind,and became my dream of visiting there again.
The 2008 Olympics provide us with the opportunity to publicize and practise environment protection in Beijing.Is it possible for Beijing to Is it possible for Beijing to become as beautiful as California?The answer is "yes",but the dream needs every Beijing citizen's full support and active moves to accomplish.
From now on,if every student who is driven to school can take bus or ride bicycle to school once a week,if every car owner goes to work in a car pool once a week,we can make a difference.If everyone can actively protect the environment in our daily life,the blue sky,green grass and lovely animals in California will appear in Beijing.
Tiny streams can combine into a vast ocean,small trees can together be an immense forest.Beijing is often described as a beautiful and aged picture.If every Beijing citizen adds a trait of green on the picture,the whole Beijing will become an ocean of green.Let us unite together to win the competition of environment protection in Beijing,and present the world a big gold medal.That is "Green Beijing,Great Olympics "

测定步骤 4.1 水样预处理:取250mL水样(如氨氮含量较高,可取适量并加水至4.3.1分取适量经絮凝沉淀预处理后的水样(使氨氮含量不超过0.1mg),加入

当然是走路,你可以假设跑每秒100公里和每秒0.01公里嘛~极限来看是走的