2009年中考数学复习教材回归知识讲解 例题解析 强化训练(二次函数与方程(组)或不等式)

2009年中考 数学 数学高考答题卡模板高考数学答题卡模板三年级数学混合运算测试卷数学作业设计案例新人教版八年级上数学教学计划 复习教材回归知识讲解 例题解析 强化训练(二次函数与方程(组)或不等式) 2009年中考数学复习教材回归知识讲解+例题解析+强化训练 二次函数与方程(组)或不等式 ?知识讲解 (1)最大值或最小值的求法 第一步确定a的符号:a>0有最小值，a<0有最大值;第二步求顶点，•顶点的纵坐标即为对应的最大值或最小值( 2 (2)y轴与抛物线y=ax+bx+c的交点为(0，c)( 22 (3)与y轴平行的直线x=h与抛物线y=ax+bx+c有且只有一个交点(h，ah+bh+c)( (4)抛物线与x轴的交点( 2 二次函数y=ax+bx+c的图像与x轴的两个交点的横坐标x，x是对应的一元二次方程12 2ax+bx+c=0的两个实数根(抛物线与x•轴的交点情况可以由对应的一元二次方程的根的判别式判定: ?有两个交点?>0抛物线与x轴相交( ,, ?有一个交点(顶点在x轴上)?=0抛物线与x轴相切; ,, ?没有交点?<0抛物线与x轴相离( ,, (5)平行于x轴的直线与抛物线的交点( 同(4)一样可能有0个交点，1个交点，2个交点(当有2个交点时，•两交点的纵坐 2标相等，设纵坐标为k，则横坐标是ax+bx+c=k的两个实数根( 2 (6)一次函数y=kx+n(k?0)的图像L与二次函数y=ax+bx+c(a?0)的图像G的交 ykxn,，,点，由方程组的解的数目确定:?当方程组有两组不同的解时L与G,,2yaxbxc,，，, 有两个交点;?方程组只有一组解时L与G只有一个交点;?方程组无解时L与G,,没有交点( (7)利用函数图像求不等式的解集，先观察图像，找出抛物线与x轴的交点，•再根据交点坐标写出不等式的解集(注意:观察图像时不要看漏了其中的部分( ?例题解析 122m 例1 如图所示，已知抛物线y=,x+(5,)x+m,3与x轴有两个交点A，B，2 点A•在x轴的正半轴上，点B在x轴的负半轴上，且OA=OB((1)求m的值;(2)求from young teachers access of website view, integrated class website of proportion highest, up 70.83%, a is integrated class website influence strong, social visibility high; II is integrated class website of various information resources rich, can meet everyone on various information resources of needs. Followed by education networks, educational networks and closely related to the work of young teachers, so the large amount of visitors, access. Third is the search engine, the Internet has been for us to expand our knowledge, sharing resources, and gain more knowledge, open a window, has become an important reason for our use of the Internet. But what is worth noting is the visitor turned out to be at least the school campus network, my school's website did not meet everyone's needs, mainly because of the small amount of resources, to meet everyone's needs, categories are not rich, and school Web site-building needs to up the horses, fast. (C) data analysis of teachers professional development 1.62nd questions what do you think of knowledge and ability of teachers ' professional development, your lack of student ... Excellent teachers of guide f. School of teachers team construction measures G. School of learning research atmosphere h. other six, and teacherson local evening, and daily of identity, and recognized; ranking third of is other, this reflect we of young teachers reading of publications also has many above by column, also description has they of reading interest widely, and dabbled in quite wide; other for not for analysis. We believe the China education daily, and as the authority of the education system of the people's education press, as too few readers of educators, not normal, it is not. 61st problem you often browse of website is () [more topics] option small meter proportion a,. integrated class website (Xinhua, and Sohu, and SINA, and Yahoo) 34 70.83% b. education network 25 52.08% c. search engine (GOOGLE Baidu) 18 37.5% d. school campus network 4 8.33% e. personal blog 16 33.33% f. professional sex website (literature network, and financial network,) 8 16.67% g. on the NET 4 8.33% h. shopping network (such as Taobao, dangdang, etc) 13 27.08% I. other types of site 5 10.42% j. do not go 0 0% k. effective fill out the passengers were not like the Internet 0 0% point 48 design point is to understand the young teacher's website. As life Internet of we, life, and work has without network has, from statistics data bar see, select "not Internet", and "not like Internet" of are for 0, also can description This is; 抛物线的解析式，并写出抛物线的对称轴和顶点C的坐标;(3)问在抛物线上是否存在一点M，?MAC???OAC，若存在，求出点M的坐标;若不存在，请说明理由( 【 分析 定性数据统计分析pdf销售业绩分析模板建筑结构震害分析销售进度分析表京东商城竞争战略分析 】抛物线与x轴交于A，B两点，OA=OB，故A，B两点关于y轴对称，就可求得m的值，由抛物线交y轴的正半轴，得m的确定值( 【解答】(1)?抛物线与y轴交于正半轴，且OA=OB( ma,,30,, ? ,250,,m,, 由?得m=?5，由?m>3，故m=,5应舍去(?m=5( 12 (2)抛物线的解析式为y=,x+2，对称轴是y轴，顶点C的坐标为C(0，2)( 2 12 (3)令y=0得 ,x+2=0，?x=?2( 2 ?A(2，0)，B(,2，0)，C(0，2)，?OAC是等腰直角三角形( 若存在一点M，使?MAC??OAC，?AC为公共边，OA=OC， ?点M与O关于直线AC对称，?M点的坐标为(2，2)( 12 当x=2时，,x+2=0?2( 2 ?M(2，2)不在抛物线上，即不存在一点M，使?MAC??OAC( 【点评】存在性问题，通常是先假定存在，若能找出具备某种条件或性质的对象，就说明存在，其叙述过程就是理由;若不存在，就需要进一步说明理由( 22 例2 已知二次函数y=x,(2m+4)x+m,4(x为自变量)的图像与y轴的交点在原点下方，与x轴交于A，B两点，点A在点B的左边，且A，B两点到原点的距离AO，OB•满足3(•OB,AO)=2AO?OB，直线y=kx+k与这个二次函数图像的一个交点为P，且锐角?POB•的正切值4( (1)求m的取值范围; (2)求这个二次函数的解析式; (3)确定直线y=kx+k的解析式( 【分析】利用抛物线与x轴的交点A，B的位置及与y轴交点的位置和A，B两点到原点的距离可以求出m的值，再利用一元二次方程根与系数的关系可以求解( 【解答】(1)设点A，B的坐标分别为A(x，0)，B(x，0)(x0( from young teachers access of website view, integrated class website of proportion highest, up 70.83%, a is integrated class website influence strong, social visibility high; II is integrated class website of various information resources rich, can meet everyone on various information resources of needs. Followed by education networks, educational networks and closely related to the work of young teachers, so the large amount of visitors, access. Third is the search engine, the Internet has been for us to expand our knowledge, sharing resources, and gain more knowledge, open a window, has become an important reason for our use of the Internet. But what is worth noting is the visitor turned out to be at least the school campus network, my school's website did not meet everyone's needs, mainly because of the small amount of resources, to meet everyone's needs, categories are not rich, and school Web site-building needs to up the horses, fast. (C) data analysis of teachers professional development 1.62nd questions what do you think of knowledge and ability of teachers ' professional development, your lack of student ... Excellent teachers of guide f. School of teachers team construction measures G. School of learning research atmosphere h. other six, and teacherson local evening, and daily of identity, and recognized; ranking third of is other, this reflect we of young teachers reading of publications also has many above by column, also description has they of reading interest widely, and dabbled in quite wide; other for not for analysis. We believe the China education daily, and as the authority of the education system of the people's education press, as too few readers of educators, not normal, it is not. 61st problem you often browse of website is () [more topics] option small meter proportion a,. integrated class website (Xinhua, and Sohu, and SINA, and Yahoo) 34 70.83% b. education network 25 52.08% c. search engine (GOOGLE Baidu) 18 37.5% d. school campus network 4 8.33% e. personal blog 16 33.33% f. professional sex website (literature network, and financial network,) 8 16.67% g. on the NET 4 8.33% h. shopping network (such as Taobao, dangdang, etc) 13 27.08% I. other types of site 5 10.42% j. do not go 0 0% k. effective fill out the passengers were not like the Internet 0 0% point 48 design point is to understand the young teacher's website. As life Internet of we, life, and work has without network has, from statistics data bar see, select "not Internet", and "not like Internet" of are for 0, also can description This is; 解得m>,2( ? 又?函数的图像与y轴的交点在原点下方， 2 ?m,4<0，?,20( 12 由3(OB,AO)=2AO?OB可得 3[x,(,x)]=2(,x)?x 2112 即3(x+x)=,2xx 1212 222 由于x，x是方程x,(2m+4)x+m,4=0的两个根，所以x+x=2m+4，x?x=m,4( 121212 2 ?3(2m+4)=,2(m,4) 2 整理，得m+3m+2=0( ?m=,1或m=,2(舍去)( 2 ?二次函数的解析式为y=x,2x,3( 2 (3)由y=x,2x,3，得A(,1，0)，B(3，0)( ?直线y=kx+k与抛物线相交， 2,yxx,,，23, ?由 ,ykxk,，,, xk,，3,x,,1,,,21 解得 或 ,,2y,0.ykk,，4.2,2, ??POB为锐角( ?点P在y轴右侧， 2 ?点P坐标为(k+3，k+4k)，且k+3>0( ?tan?POB=4， 2|4|kk， ?=4( k，3 如图所示，当点P在x轴上方时( from young teachers access of website view, integrated class website of proportion highest, up 70.83%, a is integrated class we用心 爱心 专心 bsite influence strong, social visibility high; II is integrated class website of various information resources rich, can meet everyone on various information resources of needs. Followed by education networks, educational networks and closely related to the work of young teachers, so the large amount of visitors, access. Third is the search engine, the Internet has been for us to expand our knowledge, sharing resources, and gain more knowledge, open a window, has become an important reason for our use of the Internet. But what is worth noting is the visitor turned out to be at least the school campus network, my school's website did not meet everyone's needs, mainly because of the small amount of resources, to meet everyone's needs, categories are not rich, and school Web site-building needs to up the horses, fast. (C) data analysis of teachers professional development 1.62nd questions what do you think of knowledge and ability of teachers ' professional development, your lack of student ... Excellent teachers of guide f. School of teachers team construction measures G. School of learning research atmosphere h. other six, and teacherson local evening, and daily of identity, and recognized; ranking third of is other, this reflect we of young teachers reading of publications also has many above by column, also description has they of reading interest widely, and dabbled in quite wide; other for not for analysis. We believe the China education daily, and as the authority of the education system of the people's education press, as too few readers of educators, not normal, it is not. 61st problem you often browse of website is () [more topics] option small meter proportion a,. integrated class website (Xinhua, and Sohu, and SINA, and Yahoo) 34 70.83% b. education network 25 52.08% c. search engine (GOOGLE Baidu) 18 37.5% d. school campus network 4 8.33% e. personal blog 16 33.33% f. professional sex website (literature network, and financial network,) 8 16.67% g. on the NET 4 8.33% h. shopping network (such as Taobao, dangdang, etc) 13 27.08% I. other types of site 5 10.42% j. do not go 0 0% k. effective fill out the passengers were not like the Internet 0 0% point 48 design point is to understand the young teacher's website. As life Internet of we, life, and work has without network has, from statistics data bar see, select "not Internet", and "not like Internet" of are for 0, also can description This is; 2kk，4 =4(解得k=23，k=,23( 12k，3 经检验，k=23，k=,23都是方程的解，但k+3<0( 122 3 ?k=,2舍去( 2 33 ?直线的解析式为y=2+2( 2kk，4 当点P在x轴下方时，=,4， k，3 解得k=,2，k=,6( 34 经检验，k=,2，k=,6是方程的解，但k+3<0( 344 ?k=,6舍去( 4 ?y=,2x,2( 33 ?所求直线的解析式为y=2x+2，或y=,2x,2( 【点评】本题以求解析式为目标，综合了函数，一元二次方程根与系数的关系，三角函数等知识，综合性强，灵活性大，解题关键是认真审题，认真分析纷繁复杂的条件，从中找到解题的突破口，易错点是在第(3)小题中忽视分类讨论而失解( ?强化训练 一、填空题 21(与抛物线y=2x,2x,4关于x轴对称的图像 表 关于同志近三年现实表现材料材料类招标技术评分表图表与交易pdf视力表打印pdf用图表说话 pdf 示的函数关系式是_______( 22(已知二次函数y=(a,1)x+2ax+3a,2的图像最低点在x轴上，那么a=______，此时函数的解析式为_______( 3((2006，湖北襄樊)某涵洞的截面是抛物线型，如图1所示，在图中建立的直角坐标系from young teachers access of website view, integrated class website of proportion highest, up 70.83%, a is integrated class website influence strong, social visibility high; II is integrated class website of various information resources rich, can meet everyone on various information resources of needs. Followed by education networks, educational networks and closely related to the work of young teachers, so the large amount of visitors, access. Third is the search engine, the Internet has been for us to expand our knowledge, sharing resources, and gain more knowledge, open a window, has become an important reason for our use of the Internet. But what is worth noting is the visitor turned out to be at least the school campus network, my school's website did not meet everyone's needs, mainly because of the small amount of resources, to meet everyone's needs, categories are not rich, and school Web site-building needs to up the horses, fast. (C) data analysis of teachers professional development 1.62nd questions what do you think of knowledge and ability of teachers ' professional development, your lack of student ... Excellent teachers of guide f. School of teachers team construction measures G. School of learning research atmosphere h. other six, and teacherson local evening, and daily of identity, and recognized; ranking third of is other, this reflect we of young teachers reading of publications also has many above by column, also description has they of reading interest widely, and dabbled in quite wide; other for not for analysis. We believe the China education daily, and as the authority of the education system of the people's education press, as too few readers of educators, not normal, it is not. 61st problem you often browse of website is () [more topics] option small meter proportion a,. integrated class website (Xinhua, and Sohu, and SINA, and Yahoo) 34 70.83% b. education network 25 52.08% c. search engine (GOOGLE Baidu) 18 37.5% d. school campus network 4 8.33% e. personal blog 16 33.33% f. professional sex website (literature network, and financial network,) 8 16.67% g. on the NET 4 8.33% h. shopping network (such as Taobao, dangdang, etc) 13 27.08% I. other types of site 5 10.42% j. do not go 0 0% k. effective fill out the passengers were not like the Internet 0 0% point 48 design point is to understand the young teacher's website. As life Internet of we, life, and work has without network has, from statistics data bar see, select "not Internet", and "not like Internet" of are for 0, also can description This is; 12中，抛物线的解析式为y=,x，当涵洞水面宽AB为12m时，水面到桥拱顶点O•的4 距离为_______m( 图1 图2 4((2006，山西)甲，乙两人进行羽毛球比赛，甲发出一颗十分关键的球，出手点为P，羽毛球飞行的水平距离s(m)与其距地面高度h(m)之间的关系式为h=,1232s+s+(如图2，已知球网AB距原点5m，乙(用线段CD表示)扣球的最大高1232 9度为m，•设乙的起跳点C的横坐标为m，若乙原地起跳，因球的高度高于乙扣球的4 最大高度而导致接球失败，则m的取值范围是_______( 12(若抛物线y=x与直线y=x+m只有一个公共点，则m的值为_____( 52 5218,66(设抛物线y=x+(2a+1)x+2a+的图像与x•轴只有一个交点，•则a+•323a•的值为4 _______( 27(已知直线y=,2x+3与抛物线y=x相交于A，B两点，O为坐标原点，那么?OAB•的面积等于______( 28((2008，安徽)图3为二次函数y=ax+bx+c的图像，在下列说法中: 2 ?ab<0;?方程ax+bx+c=0的根是x=,1，x=3;?a+b+c>0;?当x>1时，y随着12 x•的增大而增大( 正确的说法有_______((请写出所有正确说法的序号) 图3 图4 图5 用心from young teachers access of website view, integrated class website of proportion highest, up 70.83%, a is integrated class we 爱心 专心 bsite influence strong, social visibility high; II is integrated class website of various information resources rich, can meet everyone on various information resources of needs. Followed by education networks, educational networks and closely related to the work of young teachers, so the large amount of visitors, access. Third is the search engine, the Internet has been for us to expand our knowledge, sharing resources, and gain more knowledge, open a window, has become an important reason for our use of the Internet. But what is worth noting is the visitor turned out to be at least the school campus network, my school's website did not meet everyone's needs, mainly because of the small amount of resources, to meet everyone's needs, categories are not rich, and school Web site-building needs to up the horses, fast. (C) data analysis of teachers professional development 1.62nd questions what do you think of knowledge and ability of teachers ' professional development, your lack of student ... Excellent teachers of guide f. School of teachers team construction measures G. School of learning research atmosphere h. other six, and teacherson local evening, and daily of identity, and recognized; ranking third of is other, this reflect we of young teachers reading of publications also has many above by column, also description has they of reading interest widely, and dabbled in quite wide; other for not for analysis. We believe the China education daily, and as the authority of the education system of the people's education press, as too few readers of educators, not normal, it is not. 61st problem you often browse of website is () [more topics] option small meter proportion a,. integrated class website (Xinhua, and Sohu, and SINA, and Yahoo) 34 70.83% b. education network 25 52.08% c. search engine (GOOGLE Baidu) 18 37.5% d. school campus network 4 8.33% e. personal blog 16 33.33% f. professional sex website (literature network, and financial network,) 8 16.67% g. on the NET 4 8.33% h. shopping network (such as Taobao, dangdang, etc) 13 27.08% I. other types of site 5 10.42% j. do not go 0 0% k. effective fill out the passengers were not like the Internet 0 0% point 48 design point is to understand the young teacher's website. As life Internet of we, life, and work has without network has, from statistics data bar see, select "not Internet", and "not like Internet" of are for 0, also can description This is; 二、选择题 129((2006，绍兴)小敏在某次投篮球中，球的运动路线是抛物线y=,x+3.5的一部分(图5 4)，若命中篮圈中心，则他与篮底的距离是( ) A(3.5m B(4m C(4.5m D(4.6m 210(当m在可以取值范围内取不同的值时，代数的最小值是( ) 2742,，mm A(0 B(5 C(33 D(9 2211(二次函数y=ax+bx+c的图像如图5所示，则下列结论:?a>0，?c>0，??b,4ac>0， 其中正确的个数是( ) A(0个 B(1个 C(2个 D(3个 2212(抛物线y=x+(2m,1)x+m与x轴有两个交点，则m的取值范围是( ) 1111 A(m> B(m>, C(m< D(m<, 4444 213(根据下列表格中二次函数y=ax+bx+c的自变量x与函数y的对应值，•判断方程 2ax+bx+c=0(a?0，a，b，c为常数)的一个解x的范围是( ) x 6.17 6.18 6.19 6.20 2y=ax+bx+c ,0.03 ,0.01 0.02 0.04 A(6 方案 气瓶 现场处置方案 .pdf气瓶 现场处置方案 .doc见习基地管理方案.doc关于群访事件的化解方案建筑工地扬尘治理专项方案下载 ，并求出按此方案能获得的最大利润是多少( from young teachers access of website view, integrated class website of proportion highest, up 70.83%, a is integrated class we用心 爱心 专心 bsite influence strong, social visibility high; II is integrated class website of various information resources rich, can meet everyone on various information resources of needs. Followed by education networks, educational networks and closely related to the work of young teachers, so the large amount of visitors, access. Third is the search engine, the Internet has been for us to expand our knowledge, sharing resources, and gain more knowledge, open a window, has become an important reason for our use of the Internet. But what is worth noting is the visitor turned out to be at least the school campus network, my school's website did not meet everyone's needs, mainly because of the small amount of resources, to meet everyone's needs, categories are not rich, and school Web site-building needs to up the horses, fast. (C) data analysis of teachers professional development 1.62nd questions what do you think of knowledge and ability of teachers ' professional development, your lack of student ... Excellent teachers of guide f. School of teachers team construction measures G. School of learning research atmosphere h. other six, and teacherson local evening, and daily of identity, and recognized; ranking third of is other, this reflect we of young teachers reading of publications also has many above by column, also description has they of reading interest widely, and dabbled in quite wide; other for not for analysis. We believe the China education daily, and as the authority of the education system of the people's education press, as too few readers of educators, not normal, it is not. 61st problem you often browse of website is () [more topics] option small meter proportion a,. integrated class website (Xinhua, and Sohu, and SINA, and Yahoo) 34 70.83% b. education network 25 52.08% c. search engine (GOOGLE Baidu) 18 37.5% d. school campus network 4 8.33% e. personal blog 16 33.33% f. professional sex website (literature network, and financial network,) 8 16.67% g. on the NET 4 8.33% h. shopping network (such as Taobao, dangdang, etc) 13 27.08% I. other types of site 5 10.42% j. do not go 0 0% k. effective fill out the passengers were not like the Internet 0 0% point 48 design point is to understand the young teacher's website. As life Internet of we, life, and work has without network has, from statistics data bar see, select "not Internet", and "not like Internet" of are for 0, also can description This is; 220((2008，烟台)如图所示，抛物线L:y=,x,2x+3交x轴于A，B两点，交y•轴于1 M点(抛物线L向右平移2个单位后得到抛物线L，L交x轴于C，D两点( 122 (1)求抛物线L对应的函数表达式; 2 (2)抛物线L或L在x轴下方的部分是否存在点N，使以A，C，M，N•为顶点的四边12 形是平行四边形(若存在，求出点N的坐标;若不存在，请说明理由; (3)若点P是抛物线L上的一个动点(P不与点A，B重合)，那么点P•关于原点的对1 称点Q是否在抛物线L上，请说明理由( 2 221(已知:二次函数y=ax+bx+c的图像经过点A(0，4)，顶点在x轴上，•且对称轴在y 轴的右侧(设直线y=x与二次函数图像自左向右分别交于P(x，y)，Q(x，y)两1122 点，•且OP:PQ=1:3( (1)求二次函数的解析式; (2)求?PAQ的面积; (3)在线段PQ上是否存在一点D，使?APD??QPA，若存在，求出点D坐标，•若不 存在，说明理由( 222((2005，武汉市)已知二次函数y=ax,ax+m的图像交x轴于A(x，0)，B(x，0)12 两点，x0， 2a b ?<0，又抛物线的顶点在x轴上， a 42 ?b=16a得a=1，b=,4(b=舍去)( 9 2 ?y=x,4x+4( (2)如图所示， S=S ,S ?PAQ?AQO?APO b,1161122()4xxxx，,(),, =×4×x,×4×x=2(x,x)=2=2=29=6( 2121211222aa (3)存在点D，设D(m，n)易得P(1，1)，Q(4，4)， 5822 由?APD??QPA得PA=PQ?PD，运用勾股定理得?m,1?=，得m=或( 333 ?10)( ?直线AP的解析式为y=nx+n( 2,yxx,,,2, ,ynxn,，., 2 ?x,(n+1)x,n,2=0， ?x+x=n+1， AP ?x=n+2( P 111 又S =S +S =CD?AO+CD?x=CD(AO+x)( ?PAC?ADC?PDCpp222 12 ?(n+2)(1+n+2)=6，n+5n,6=0( 2 ?n=,6(舍去)或n=1( ?在第一象限，抛物线上存在点P(3，4)，使S =6( ?PAC 用心from young teachers access of website view, integrated class website of proportion highest, up 70.83%, a is integrated class we 爱心 专心 bsite influence strong, social visibility high; II is integrated class website of various information resources rich, can meet everyone on various information resources of needs. Followed by education networks, educational networks and closely related to the work of young teachers, so the large amount of visitors, access. Third is the search engine, the Internet has been for us to expand our knowledge, sharing resources, and gain more knowledge, open a window, has become an important reason for our use of the Internet. But what is worth noting is the visitor turned out to be at least the school campus network, my school's website did not meet everyone's needs, mainly because of the small amount of resources, to meet everyone's needs, categories are not rich, and school Web site-building needs to up the horses, fast. (C) data analysis of teachers professional development 1.62nd questions what do you think of knowledge and ability of teachers ' professional development, your lack of student ... Excellent teachers of guide f. School of teachers team construction measures G. School of learning research atmosphere h. other six, and teacherson local evening, and daily of identity, and recognized; ranking third of is other, this reflect we of young teachers reading of publications also has many above by column, also description has they of reading interest widely, and dabbled in quite wide; other for not for analysis. We believe the China education daily, and as the authority of the education system of the people's education press, as too few readers of educators, not normal, it is not. 61st problem you often browse of website is () [more topics] option small meter proportion a,. integrated class website (Xinhua, and Sohu, and SINA, and Yahoo) 34 70.83% b. education network 25 52.08% c. search engine (GOOGLE Baidu) 18 37.5% d. school campus network 4 8.33% e. personal blog 16 33.33% f. professional sex website (literature network, and financial network,) 8 16.67% g. on the NET 4 8.33% h. shopping network (such as Taobao, dangdang, etc) 13 27.08% I. other types of site 5 10.42% j. do not go 0 0% k. effective fill out the passengers were not like the Internet 0 0% point 48 design point is to understand the young teacher's website. As life Internet of we, life, and work has without network has, from statistics data bar see, select "not Internet", and "not like Internet" of are for 0, also can description This is;