机械原理练习及答案

第二章 平面机构的结构分析2-1 绘制图示机构的运动简图。 2-3 计算图示机构的自由度，并指出复合铰链、局部自由度和虚约束。 解：(a) C处为复合铰链。ph=0，pl=10。自由度 。(b) B处为局部自由度，应消除。， ph=2，pl=2自由度 。(c) B、D处为局部自由度，应消除。， ph=2，pl=2。自由度 。(d) CH或DG、J处为虚约束，B处为局部自由度，应消除。，ph=1，pl=8。自由度 。(e) 由于采用对称结构，其中一边的双联齿轮构成虚约束，在连接的轴颈处，外壳与支架处的连接构成一个虚约束转动副,双联齿轮与外壳一边构成虚约束。其中的一边为复合铰链。其中，ph=2，pl=4。自由度 。(f) 其中，ph=0，pl=11。自由度 。(g) 当未刹车时，ph=0，pl=8，刹车机构自由度为 当闸瓦之一刹紧车轮时，ph=0，pl=7，刹车机构自由度为 当两个闸瓦同时刹紧车轮时，ph=0，pl=6，刹车机构自由度为2-3 判断图示机构是否有确定的运动，若否，提出修改方案。 分析 (a) 要分析其运动是否实现设计意图，就要计算机构自由度，不难求出该机构自由度为零，即机构不能动。要想使该机构具有确定的运动，就要设法使其再增加一个自由度。（b）该机构的自由度不难求出为3，即机构要想运动就需要3个原动件，在一个原动件的作用下，无法使机构具有确定的运动，就要设法消除两个自由度。解： （a）机构自由度 。该机构不能运动。修改措施：（1）在构件2、3之间加一连杆及一个转动副（图a-1所示）；（2）在构件2、3之间加一滑块及一个移动副（图a-2所示）；（3）在构件2、3之间加一局部自由度滚子及一个平面高副（图a-3所示）。（4）在构件2、4之间加一滑块及一个移动副（图a-4所示） 修改措施还可以提出几种，如杠杆2可利用凸轮轮廓与推杆3接触推动3杆等。（b）机构自由度 。在滑块的输入下机构无法具有确定的运动。修改措施（1）构件3、4、5改为一个构件，并消除连接处的转动副（图b-1所示）；（2）构件2、3、4改为一个构件，并消除连接处的转动副（图b-2所示）；（3）将构件4、5和构件2、3分别改为一个构件，并消除连接处的转动副（图b-3所示）。第三章 平面机构的运动分析3-1 试确定图示各机构在图示位置的瞬心位置。解：瞬心的位置直接在题图上标出。图3-13-2 在图示四杆机构中，=60mm，=90mm，=120mm，=10rad/s，试用瞬心法求： (1)当=45时，点C的速度； (2)当=165时，构件3的线上(或其延长线上)速度最小的一点E的位置及其速度大小；(3)当=0时，角之值(有两个解)。 解：以选定的比例尺作机构运动简图如图3-2所示。（1）定瞬心P13的位置，求vc。（2）如图（b）所示，定出构件2的BC线上速度最小的一点E位置及速度的大小。因为BC线上速度最小之点必与P24点的距离最近，故从P24点引BC线的垂线交于点E，由图可知 （3）定出的两个位置见图（c）所示，量出，。第四章 平面机构的力分析4-1 图a和b所示两种牛头刨床机构，已知：=580mm，=260mm，=960mm；从动件5上作用工作阻力=200N。试分别求两机构的平衡力矩。 图4-14-2 在图示曲柄摆动导杆机构中，已知：=150mm，=360mm；、和分别为构件1、2和3的质心，=200mm；构件3质量=10kg，转动惯量=0.2kgm2；=100rad/s(常数)。试求平衡力矩及各运动副中反力。图4-2第五章 机械效率5-1 填空题 (1)槽面摩擦比平面摩擦力大是因为 。 (2)从受力观点分析，移动副的自锁条件是 ；转动副的自锁条件是 ；从效率观点分析，机械自锁的条件是 。 (3)三角螺纹比矩形螺纹摩擦 。故三角螺纹多用于 矩形螺纹多应用于 。5-2 比较各种螺纹当量摩擦系数的大小。已知螺纹的牙形角。 题5-25-4 如图所示的双滑块机构中，设已知mm，转动副A、B处轴颈直径mm，转动副处的摩擦系数=0.15，移动副处的摩擦系数=0.1，试求： (1)与的关系式，且=45，=100N时，=? (2)在力为驱动力时，机构的自锁条件(不计各构件的重力)。解：题5-35-6 图示为一颚式破碎机在破碎矿石时要矿石不至被向上挤出，试问角应满足什么条件?经分析你可得出什么结论? 题5-6图 题5-6解图解：设矿石的重量为Q，矿石与鄂板间的摩擦因数为f，则摩擦角为 矿石有向上被挤出的趋势时，其受力如图所示，由力平衡条件知：即 当时，即，矿石将被挤出，即自锁条件为。第六章 平面连杆机构63 在图示铰链四杆机构中，各杆长度分别为=28mm，=52mm，=50mm，=72mm。 (1) 若取为机架，求该机构的极位夹角，杆的最大摆角和最小传动角；(2) 若取为机架，该机构将演化成何种类型的机构?为什么?请说明这时、两个转动副是周转副还是摆转副?题6-3 题6-3解图解：（1）作出机构的两个极位，如图所示，并由图中量得 ，所以 。（2）由可知，所示的铰链四杆机构各杆长度符合杆长条件；当取最短杆1为机架时，该机构将演化成双曲柄机构；最短杆1参与构成的转动副A，B都是周转副，而C，D为摆转副。64 在图示的连杆机构中，已知各构件的尺寸为=160mm，=260mm，=200mm，=80mm；并已知构件为原动件，沿顺时针方向匀速回转，试确定： (1) 四杆机构的类型； (2) 该四杆机构的最小传动角；(3) 滑块的行程速比系数。解：（1）由且最短杆AD为机架可知，题中的四杆机构ABCD为双曲柄机构。 （2）作出四杆机构ABCD传动角最小时的位置，如题6-4解图所示，并量得，所以，。（3）作出滑块F的上、下两个极位及原动件AB与之对应的两个极位，并量得，求出滑块F的行程速比系数为 行程速比系数为。 题6-4 题6-4解图68 如图示，设已知破碎机的行程速比系数=1.2，颚板长度=300mm，颚板摆角，曲柄长度=80mm，求连杆的长度，并检验最小传动角是否符合要求。 题6-8图 题6-8解图解：先计算极位夹角： 取相应比例尺1作出摇杆CD的两极限位置C1D和C2D和固定铰链A所在圆s1（保留作图线）。 如图（题6-8解图）所示，以C2为圆心，2AB为半径作圆，同时以F为圆心，2FC2为半径作圆，两圆交于点E，作C2E的延长线与圆s1的交点，即为铰链A的位置。由图知： 610 图示六杆机构。已知=200mm，=585mm，=300mm，=700mm，试求： (1) 机构的行程速比系数； (2) 构件5的冲程； (3) 机构最大压力角发生的位置及大小；(4) 在其它尺寸不变的条件下，欲使冲程为原冲程的2倍，问曲柄长度为多少? 题6-10图第七章 凸轮机构73 图(a)所示为自动闪光对焊机机构简图。其中凸轮1为主动件，通过滚子2推动滑板3移动进行焊接。滑板所需运动规律如图b所示。设已知凸轮的最小半径=90mm，滚子半径=15mm，试用反转法绘制凸轮轮廓(建议画图时用=2mm/mm，=8/mm，推程的分点间隔20，回程的分点间隔10)。题7-3图74 设计一偏置移动滚子从动件盘形凸轮机构。凸轮回转方向和从动件初始位置如图所示。已知偏距=10mm，基圆半径=40mm，滚子半径=10mm。从动件的运动规律如下：=180,=30，=120，=30，从动件在推程中以简谐运动规律上升，升程=30mm；回程以等加速等减速运动规律返回原处。试用图解法绘制从动件位移线图及凸轮轮廓(要求推程和回程的分点数6个)。 题7-4图 题7-6图76 已知：凸轮机构摆杆的运动规律，摆杆长=120mm，凸轮以逆时针等速转动，其理论基圆半径=100mm，滚子半径=15mm，如图所示，试设计盘形凸轮的轮廓曲线。77 设计一平底摆动从动件盘形凸轮机构。凸轮回转方向和从动件初始位置如图所示。已知=75mm，=30mm，从动件运动规律如下:=180,=0，=180，=0，从动件推程以简谐运动规律顺时针摆动，=20；回程以等加速等减速运动规律返回原处。试用图解法绘出凸轮轮廓，并确定从动件的长度(要求分点间隔30)。题7-7图79 已知从动件的运动规律如图a所示。机构简图如图b所示。已知基圆半径=30mm，偏距=15mm。求：1)尖底接触，凸轮顺时针转动时，试用图解法绘制凸轮轮廓。2)尖底接触，凸轮逆时针转动时，用图解法绘出凸轮轮廓。3)从动件改为滚子接触时，取滚子半径=10mm，凸轮逆时针转动，用图解法绘出凸轮轮廓。4)在图上量出上列各轮廓在=60时的压力角，并比较之。同时比较在2和3两种情况下的运动失真(作图时分点角度20)。题7-9图第八章 齿轮机构8-2 一对渐开线齿廓如图所示，两渐开线齿廓啮合于点，试求： (1) 当绕点转动的齿廓为主动及啮合线如图中时，确定两齿廓的转动方向； (2) 用作图法标出渐开线齿廓上与点，相啮合的点，； (3) 用阴影线标出两条渐开线齿廓的齿廓工作段； (4) 齿廓上段与齿廓上段相比较，哪一个较短，这说明什么问题； (5) 在图上标出这对渐开线的节圆和啮合角。题8-2图8-4 有一个渐开线直齿圆柱齿轮如图所示，用卡尺测量出三个齿和两个齿的反向渐开线之间的法向齿距(即公法线长度)分别为=61.84mm和=37.56mm，齿顶圆直径=208mm，齿根圆直径=172mm，数得其齿数=24，试求：(1) 该齿轮的模数，分度圆压力角、齿顶高系数和顶隙系数；(2) 该齿轮的基圆齿距和基圆齿厚。题8-4图8-5 已知一对渐开线外啮合标准直齿圆柱齿轮机构，=20，=1，=4mm，=18，=41。试求： (1) 标准安装时的重合度； (2) 用作图法画出理论啮合线，在其上标出实际啮合线段，并标出单齿啮合区和双齿啮合区，以及节点的位置。解：（1）求重合度： 其实际啮合线长度：题8-5解图 （2）理论啮合曲线和实际啮合曲线以及啮合区如图题8-5解图所示。8-7 测量齿轮的公法线长度是检验齿轮精度的常用方法之一，试用图证明渐开线齿轮公法线长度和卡尺跨的齿数的计算公式：式中为被测齿轮的齿数，为卡尺跨的齿数，目的是为了卡尺必须卡在渐开线齿廓上。题8-7图8-8 某牛头刨床中，有一对渐开线外啮合标准齿轮传动，已知=17，=118，=5mm，=1，=337.5mm。检修时发现小齿轮严重磨损，必须报废。大齿轮磨损较轻，沿分度圆齿厚共需磨0.75mm，可获得光滑的新齿面，拟将大齿轮修理后使用，仍用原来的箱体，试设计这对齿轮。解：（1）确定传动类型： 因，故应采用等移距变位传动。（2）确定两轮变位系数，由题意知故 （3）计算几何尺寸（单位：mm），如下表尺寸名称小齿轮大齿轮分度圆直径齿顶高齿根高齿顶圆直径齿根圆基圆直径分度圆齿厚分度圆齿槽厚周节8-13 一对渐开线标准平行轴外啮合斜齿圆柱齿轮机构，其齿数=23，=53，=6mm，=20，=1，=0.25，=236mm，=25mm，试求： (1) 分度圆螺旋角； (2) 当量齿数和； (3) 重合度。解：（1）计算分度圆螺旋角： （2）当量齿数：（3）计算重合度： 所以齿轮传动的重合度为1.94。第九章 轮系91 图示为一手摇提升装置，其中各轮齿数均为已知，试求传动比，并指出当提升重物时手柄的转向。 题9-1图解：92 图示轮系中，已知各轮齿数为=60，=20，=20，=20，=20，=100，试求传动比。解：为求解传动比，可以将该轮系划分为由齿轮1、2、2、5和行星架H所组成的行星轮系，得 由得 ， （1）由齿轮2，3，4，5和行星架H所组成得行星轮系，得 （2） 由（1）和（2）式得 传动比为 。 95 在图示的电动三爪卡盘传动轮系中，设已知各轮齿数为：=6，=25，=57，=56，试求传动比。解：此轮系为一个3K型行星轮系，即有三个中心轮（1，3及4）。若任取两个中心轮和与其相啮合行星轮及系杆H便组成一个2K-H型的行星轮系。且有三种情况：1-2-3-H行星轮系、4-2（2）-3-H行星轮系及1-2（2）-4-H差动轮系。而仅有两个轮系是独立的，为了求解简单，常选两个行星轮系进行求解，即故该行星轮系传动比为 （和转向相反）97 图示为一种大速比减速器的示意图。动力由齿轮1输入，H输出。已知各轮齿数为：=12，=51，=76，=49，=12，=73。 (1) 试求传动比。 (2) 若将齿轮2的齿数改为52(即增加一个齿)则传动比又为多少? 题9-7图 题9-10图910 汽车自动变速器中的预选式行星变速器如图示。轴为主动轴，轴为从动轴，为制动带。其传动有两种情况：(1) 压紧齿轮3，处于松开状态；(2) 压紧齿轮6，处于松开状态。已知各轮齿数为=30，=30，=90，=40，=25。试求两种情况下的传动比i。912 在图示的轮系中，轮1与电动机轴相联，=1440r/min，=20，=60，=90，=210，求=?第十章 间歇运动机构10-1 在牛头刨床中工作台的进给机构中，已知棘轮最小转动角度=9，棘轮模数=5mm，工作台进给螺杆的导程=6mm。试求：(1)棘轮的齿数；(2)工作台的最小送进量。10-2 设计一外啮合棘轮机构，已知棘轮的模数=10mm，棘轮的最小转角=12,试求：(1) 棘轮的；(2) 棘爪的长度。10-3 在图所示的内槽轮机构中，已知槽轮槽数=4，拔盘上装有一个圆销。试求：(1) 该槽轮机构的运动系数；(2) 当销轮以等角速度=10rad/s转动时，槽轮在=100处的角速度和角加速度。10-4 六角车床上六角刀架转位用的外啮合槽轮机构，其中心距=100mm，槽数=6，圆销数=1，要求停歇时间，试求外径=50mm的转台(转台与槽轮固联为一体)转动时的最大圆周速度。10-5 填空：(1) 当主动件做等速度连续转动，需要从动件做单向间歇转动时，可采用 ， 机构。(2) 在间歇运动机构中，当需要从动件的动程可无级调节时，可采用 机构。(3) 在棘轮机构中，棘爪能顺利滑过棘轮齿根部的条件是 。第十一章其他常用机构11-1 图示为一机床上带动溜板2和导轨3上移动的微动螺旋机构。螺杆1上有两段旋向均为右旋的螺纹，段的导程=1mm，段的导程=0.75mm。试求当手轮按向顺时针转动一周时，溜板2相对于导轨3移动的方向及距离大小。又若将段螺纹的旋向改为左旋，而段的旋向及其它参数不变，试问结果又将如何?题11-1图11-2 在图示的凸轮连杆机构中(尺寸和位置如图所示)，拟使点的运动轨迹为图示的a b c a曲线。试设计机构中的凸轮1和凸轮2的轮廓。题11-2图 题11-4图11-4 在图示齿轮连杆组合机构中，曲柄1为主动件，内齿轮5为输出构件。已知齿轮2，5的齿数为曲柄长度为，连杆长度为，试写出输出构件齿轮5的角速度与主动曲柄1的角速度之间的关系式。第十三章 机械动力学13-1 在图示平面六杆机构中，已知：100mm，=90，=10kg，=0.05kgm2，=0.01kgm2，=0.04kgm2，=1kN。设取曲柄1为等效构件，求等效转动惯量及工作阻力引起的等效阻力矩。 题13-1图 题13-2图13-2 图示由行星轮系和蜗杆蜗轮机构组成的减速装置，已知各轮齿数：=20，=60，=1(单头)，=40；各轮及行星架的质心均在其几何轴线上，两个行星轮2对称布置；各回转轴系的转动惯量(kgm2)：=0.001，=0.001，=0.016，=1.6；行星轮2质量=1.25kg；齿轮1、2和3的模数=4mm。 1) 设取轮1为等效构件，求等效转动惯量；2) 欲使卷绕在鼓轮(=100mm)上=1kN的重物，等速上升，求作用在轮1上的驱动力矩。13-3 如图示定轴轮系，已知各轮齿数：=20，=30，=40，各轮转动惯量(kgm2)：=0.1，=0.225，=0.4；力矩(Nm)：=80，=100。求从起动开始经1秒钟时轮1的角加速度及角速度。 题13-3图 题13-4图13-4 在某机械系统中，取其主轴为等效构件，平均转速=1000r/min，等效阻力矩如图所示。设等效驱动力矩为常数，且除飞轮以外其它构件的转动惯量均可忽略不计，求保证速度不均匀系数不超过0.04时，安装在主轴上的飞轮转动惯量。设该机械由电动机驱动，所需平均功率多大?如希望把此飞轮转动惯量减小一半，而保持原来的值，则应如何考虑?13-5 图示行星轮系中，已知各轮齿数为=20。=60，各构件的质心均在其相对回转轴线上，它们的转动惯量为=0.01kgm2，=0.1kgm2，行星轮2的质量=2kg，模数=10mm，作用在行星架上的力矩=40Nm。求构件1为等效构件时的等效力矩和等效转动惯量。题13-5图第十四章 机械平衡14-1 图示为摆动活齿减速器偏心盘激波器，其直径为=100mm，偏心距为=8mm，轴孔直径为=20mm。要求在该偏心盘上开23个圆孔达到静平衡，试设计确定所开孔的大小和位置。14-2 图示凸轮轴系由三个相互错开120的偏心轮组成，每个偏心轮的质量为0.5kg，其偏心距为12mm，若在平衡基面、内回转半径为=10mm处加一平衡质量和使之平衡。试求和的大小和方位。14-3 图示为一行星轮系，各轮为标准齿轮，其齿数=58，=42，=44，=56，模数均为=5mm，行星轮2-轴系本身已平衡，质心位于轴线上，其总质量=2kg。问： 1) 行星轮2-轴系的平衡质径积为多少? 2) 采用什么措施加以平衡? 题14-1图 题14-2图 题14-3图 题14-4图14-4 如图示机构中各杆长=50mm，=150mm，=130mm，=200mm；其质量=1kg，=2kg，=6kg，质心位于各自构件的中点。试在构件1、3上加平衡质量来实现机构惯性力的完全平衡。第十五章 机械系统的方案设计15-1 试分析图中两机构是否具有相同的运动特性，并说明理由。题15-1图15-4 自动打印机的方案设计 (1) 工作原理及工艺过程 在包装好的商品纸盒上打印记号。工艺过程为：将包装好的商品送至打印工位；夹紧定位后打印记号；将产品输出。 (2) 原始数据及设计要求 1) 纸盒尺寸为：长100150mm，宽70100mm，高3050mm； 2) 产品质量约为0.51kg； 3) 生产率为80次/min； 4) 要求结构简单紧凑，运动灵活可靠，便于制造。 (3) 设计任务 1) 进行送料夹紧机构、打印机构和输出机构的方案拟定，要求各有3个以上的预选方案； 2) 进行方案的评价和决策； 3) 绘制机械执行系统的方案示意图； 4) 拟定机械运动循环图； 5) 对执行系统进行尺度设计。15-6 图示为电动绞车的三种传动系统方案。试从结构、性能、经济性及对工作条件的适应性等方面对该三种方案加以比较。题15-6图1电动机；2，5连轴器；3制动器；4减速器；6卷筒；7轴承；8开式齿轮传动5-7 今需设计一台如图a所示的带式运输机的传动系统。运输机的工作状况为两班制，连续单向运转；运输带的工作速度为=1.1m/s(允许误差为5%)，拉力为=7kN，载荷平稳。工作环境为室内，灰尘较大，最高温度35。滚筒直径D=400mm。 试对图bg所示的参考传动方案，分别就其传动类型及特点进行分析和比较，并对传动链中机构的安排顺序进行评价。最后选择一个较佳的方案，或自行设计一个改进后的方案。 （英文版 ） easily blame, to prevent the broken window effect. Supervise the leading cadres to play an exemplary role, take the lead in the strict implementation of the and , lead to safeguard the solemnity and authority of the party discipline, ensure that the party discipline and the laws and regulations for implementation in place. Throughout the discipline in the daily supervision and management, strengthen supervision and inspection, from the thorough investigation of violations of discipline behavior. Strengthen to key areas, key departments and key projects as well as the masses reflect the concentration of the units and departments for supervision. - strengthening supervision, discipline inspection and supervision of cadres to set an example for compliance with the and is a man must be hexyl, blacksmith needs its own hardware. Discipline inspection organs as the executor of the party discipline, and supervisor of the defenders, for its supervision must be more strictly, discipline inspection and supervision of cadres to firmly establish the awareness of Party Constitution, sense of discipline and rules consciousness, politics loyalty, sense obey. Action speak Ji Ordinance to set an example of the regulations of the rule of law, strengthen supervision and accept the supervision of the firmness and consciousness, do comply with and . To firmly establish the discipline must first be disciplined, the supervisor will be subject to the supervision of concept, and consciously safeguard and implement party compasses party, take the lead in practicing three strict real strict, so loyal, clean, play. To be good at learning, the Constitution and the as morality, politics and brought to fruition; to implement , do not want to, dare not, not with disciplinary ruler to supervision; to discipline a ruler, often the control inspection, and consciously in the ideological red line to draw the row Ming Good accumulation is indeed the bottom line, so that the heart has fear, said to have quit, the line has ended. Attached: indifferent to heart, calmly to the table in our life, there are many unpredictable things will happen, some good, some bad things, we cannot control is powerless to stop, but with time, you will find in life sometimes turns out to be not good, some bad things finally turned out to be a good thing, but then we muddy however did not know, this is the life teach us things. 1, life can be complex, can also be simple. Want simple life of precipitation, to have enough time to reflect, to make Become more perfect. Life is the most important thing is not to win, but the struggle; not to have conquered, but to have fought well. 2, the plain is the background of life. Live a plain life, give up on themselves is not a coward, but the wise answers; not disillusioned after the heart, such as ashes, but experience the storm after the enlightenment; not unrewarding perfunctorily, but calm attitude of life of unrestrained self-confidence. Plain living, there is no noise noisy, no earthly troubles, more did not fill in the discontent of desire, some just a calm, a calm. 3, memory of heart will not good things to erase the, life is a When no movie, pain is a beginning, the struggle is a kind of process, death is a kind of ending. Give up this giving up is the helpless, do not give up the abandoned, do not give up this giving up is ignorance, do not give up should not give up is persistent. 4, a thing figured is heaven, think impassability is hell. Since the living, to live better. Sometimes we because of too narrow-minded, too care around the chores and penny wise and pound foolish, not worth the candle. Some things to attract trouble and worry, completely depends on how we look at and deal with it. Dont always take everything back to things, and dont get into a blind alley, dont want to face, dont be narrow-minded. Poke to care, is a kind of open-minded, a free and easy. 5, I am not afraid of others behind me a knife, I afraid to look back and see stab me, is my intention to treat people; I am not afraid of the truth to tell the best friend, Im afraid he turned to it as a joke to tell dont 6, when we are in a positive frame of mind, you will find many good things; and when we are in a negative state of mind, you will find many depressed things; life happy and worry, all is you of life attitude, optimistic, good luck; loss of sink, Eritrea company. When you are in adversity, may wish to change a point of view to think everything over to the good Think, because good mentality decided the fate of the! 7, people are tired, rest; heart tired, calm. Grow up, mature, this society read. Tired and sad, squat down, to their a hug. Because the world no one can sympathize with you, have mercy on you. You cry, tears is your own; you pain, no one can understand. Then you only tears to smile. 8, each people have youth,Each youth are a story, the life of the world never gets easier, I want what, wish the world all know, as has been the same; now want anything, for fear that others know, or like to lose the same. 9, the heart move, everything in the world is followed by birth, Rangrang, important thing is often the most difficult to open ones mouth, because words will reduce its importance; to let strangers people care about your life in the good things, the original is not easy 10, do not blame, do not laugh at who, also dont envy who. Like a person is a kind of feeling, not like a person is true. The truth is easy to explain, I feel Is unspeakable. The best travel life is that you in a strange place found a long lost touched. 11, happy life not in the bustling in, and in the peace of mind; no matter how many grievances, how uncomfortable, and ultimately to heal themselves or their own, others may got you to comfort, but never know your heart is how wanjianchuanxin. 12, maam, like a movie, learn to appreciate, learn to be grateful, learn tolerance, and goodness, helping others. Instead of accusing the society, as into one; and an exception is better to give than to what 13, dont envy him A sum of, dont lose your life and the life, respectively is: the former is a we experienced cannot escape in a day finally will last minute, while the latter is our persistent, we want to cherish the memory of those people and things. 14, learn to smile, learn to strong, the world you know so many people, so many people and you are, you cannot change also cant let everyone like you, so also do not want to do. Life is too short to go crazy to love to go to waste, to chase the dream to regret. 15, when temper, a blessing to go. A wounding elegant people, the key is to control their own emotions. With the mouth is the most stupid behavior. A control negative emotions than a can take a city more powerful water flow slow, language is expensive. People spent two years of time to learn to speak, but to spend a few years time to shut up. That is a kind of ability, that is a kind of wisdom. 16, life is not perfect, sometimes, growth is not a cry, not an eyeful of tears, there is no trace of emotion, there is no gleam of hope, no desire, no action, no static, there is only one kind of downward sinking feeling, sink A murky? 6? 7? 6? 7 sink? 6? 7? 6? 7 toward the bottom of the sink. 17, in some way, do not go, you will not know the other side scenery is beautiful. To you is not good, you do not mind too much, no one has an obligation to you; you learn knowledge, is you have weapons, you can start from scratch, but not unarmed; how do you treat people, does not represent how others treat you, if cannot see through this point, only inviting worry. 18, time is like a sponge in the water, as long as you are willing to squeeze, the total water is still there. Every life, after the ups and downs The best test of live, to life, survival and continuation, do not stop the struggle in the joys and sorrows of life on the road, so that different soul to bear life beat, acceptance of suffering. 19, indifferent to heart, calmly in table, elegant and comfortable life, do not take what is so important. The pursuit will be disappointed; to be alive, you will have trouble. Life is the most afraid of what all want to care about, but also what all grasp is not firm, without scenery, separated populations, such as not to desire, all docked in the fate of the end. Why is too rigid, the natural, to go stay not to live, let go of obsession, revel is 20, if the fate of the broken Hopes of sailing, please dont despair, the coast is still, if the fate of the withered petals of the beautiful, please do not sink, the spring is still, life will always be endless trouble, please dont helpless, because they are still alive, is still a dream, the sun still, we still. Lost, keep memories; to get, must work to; but the most important is good to cherish their own. 21, life, select the complex, is to choose the pain; choose a simple, is choose to be happy. The complex world like aSignificance of pride. Hope is the ornate palace, outside people admiring the magnificent, living in the deep knowledge of living it to pay the price. Simple world as a simple log cabin outside ridiculed shabby, the heart is willing to go live to know the joy. Suffering and joy is their own choice. 22, learn how to use a single powerful heart, let the past be the past, let the future come. Life is really the end of the end of an eagle is flying wings, life is constantly pursuit. Dont miss to regret, dont wait for old just miss. Time to return, seize every moment, again painstakingly again tired also Those struggling to fly. 23, life could not Yimapingchuan, even flat pavement, inevitably there will be a few pieces of roadblocks. Some of the rocks around the past, while others have to move it out. Just move others put the stone is very easy, because the stone from the appearance we can discern; difficult to myself to move away the heart of stone head. Leave time to spend with her, often reflect my